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2017-09-08block/cfq: cache rightmost rb_nodeDavidlohr Bueso1-5/+14
For the same reasons we already cache the leftmost pointer, apply the same optimization for rb_last() calls. Users must explicitly do this as rb_root_cached only deals with the smallest node. [dave@stgolabs.net: brain fart #1] Link: http://lkml.kernel.org/r/20170731155955.GD21328@linux-80c1.suse Link: http://lkml.kernel.org/r/20170719014603.19029-18-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08block/cfq: replace cfq_rb_root leftmost cachingDavidlohr Bueso1-50/+20
... with the generic rbtree flavor instead. No changes in semantics whatsoever. Link: http://lkml.kernel.org/r/20170719014603.19029-11-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-28block, scheduler: convert xxx_var_store to voidweiping zhang1-7/+6
The last parameter "count" never be used in xxx_var_store, convert these functions to void. Signed-off-by: weiping zhang <zhangweiping@didichuxing.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-11cfq: Give a chance for arming slice idle timer in case of group_idleRitesh Harjani1-1/+2
In below scenario blkio cgroup does not work as per their assigned weights :- 1. When the underlying device is nonrotational with a single HW queue with depth of >= CFQ_HW_QUEUE_MIN 2. When the use case is forming two blkio cgroups cg1(weight 1000) & cg2(wight 100) and two processes(file1 and file2) doing sync IO in their respective blkio cgroups. For above usecase result of fio (without this patch):- file1: (groupid=0, jobs=1): err= 0: pid=685: Thu Jan 1 19:41:49 1970 write: IOPS=1315, BW=41.1MiB/s (43.1MB/s)(1024MiB/24906msec) <...> file2: (groupid=0, jobs=1): err= 0: pid=686: Thu Jan 1 19:41:49 1970 write: IOPS=1295, BW=40.5MiB/s (42.5MB/s)(1024MiB/25293msec) <...> // both the process BW is equal even though they belong to diff. cgroups with weight of 1000(cg1) and 100(cg2) In above case (for non rotational NCQ devices), as soon as the request from cg1 is completed and even though it is provided with higher set_slice=10, because of CFQ algorithm when the driver tries to fetch the request, CFQ expires this group without providing any idle time nor weight priority and schedules another cfq group (in this case cg2). And thus both cfq groups(cg1 & cg2) keep alternating to get the disk time and hence loses the cgroup weight based scheduling. Below patch gives a chance to cfq algorithm (cfq_arm_slice_timer) to arm the slice timer in case group_idle is enabled. In case if group_idle is also not required (including for nonrotational NCQ drives), we need to explicitly set group_idle = 0 from sysfs for such cases. With this patch result of fio(for above usecase) :- file1: (groupid=0, jobs=1): err= 0: pid=690: Thu Jan 1 00:06:08 1970 write: IOPS=1706, BW=53.3MiB/s (55.9MB/s)(1024MiB/19197msec) <..> file2: (groupid=0, jobs=1): err= 0: pid=691: Thu Jan 1 00:06:08 1970 write: IOPS=1043, BW=32.6MiB/s (34.2MB/s)(1024MiB/31401msec) <..> // In this processes BW is as per their respective cgroups weight. Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29block: use standard blktrace API to output cgroup info for debug notesShaohua Li1-9/+6
Currently cfq/bfq/blk-throttle output cgroup info in trace in their own way. Now we have standard blktrace API for this, so convert them to use it. Note, this changes the behavior a little bit. cgroup info isn't output by default, we only do this with 'blk_cgroup' option enabled. cgroup info isn't output as a string by default too, we only do this with 'blk_cgname' option enabled. Also cgroup info is output in different position of the note string. I think these behavior changes aren't a big issue (actually we make trace data shorter which is good), since the blktrace note is solely for debugging. Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-12Merge tag 'v4.12-rc5' into for-4.13/blockJens Axboe1-2/+15
We've already got a few conflicts and upcoming work depends on some of the changes that have gone into mainline as regression fixes for this series. Pull in 4.12-rc5 to resolve these conflicts and make it easier on down stream trees to continue working on 4.13 changes. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-05-31cfq-iosched: fix the delay of cfq_group's vdisktime under iops modeHou Tao1-2/+15
When adding a cfq_group into the cfq service tree, we use CFQ_IDLE_DELAY as the delay of cfq_group's vdisktime if there have been other cfq_groups already. When cfq is under iops mode, commit 9a7f38c42c2b ("cfq-iosched: Convert from jiffies to nanoseconds") could result in a large iops delay and lead to an abnormal io schedule delay for the added cfq_group. To fix it, we just need to revert to the old CFQ_IDLE_DELAY value: HZ / 5 when iops mode is enabled. Despite having the same value, the delay of a cfq_queue in idle class and the delay of cfq_group are different things, so I define two new macros for the delay of a cfq_group under time-slice mode and iops mode. Fixes: 9a7f38c42c2b ("cfq-iosched: Convert from jiffies to nanoseconds") Cc: <stable@vger.kernel.org> # 4.8+ Signed-off-by: Hou Tao <houtao1@huawei.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-30cfq-iosched: Delete unused function min_vdisktime()Matthias Kaehlcke1-9/+0
This fixes the following warning when building with clang: block/cfq-iosched.c:970:19: error: unused function 'min_vdisktime' [-Werror,-Wunused-function] Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-05cfq: Disable writeback throttling by defaultJan Kara1-12/+5
Writeback throttling does not play well with CFQ since that also tries to throttle async writes. As a result async writeback can get starved in presence of readers. As an example take a benchmark simulating postgreSQL database running over a standard rotating SATA drive. There are 16 processes doing random reads from a huge file (2*machine memory), 1 process doing random writes to the huge file and calling fsync once per 50000 writes and 1 process doing sequential 8k writes to a relatively small file wrapping around at the end of the file and calling fsync every 5 writes. Under this load read latency easily exceeds the target latency of 75 ms (just because there are so many reads happening against a relatively slow disk) and thus writeback is throttled to a point where only 1 write request is allowed at a time. Blktrace data then looks like: 8,0 1 0 8.347751764 0 m N cfq workload slice:40000000 8,0 1 0 8.347755256 0 m N cfq293A / set_active wl_class: 0 wl_type:0 8,0 1 0 8.347784100 0 m N cfq293A / Not idling. st->count:1 8,0 1 3814 8.347763916 5839 UT N [kworker/u9:2] 1 8,0 0 0 8.347777605 0 m N cfq293A / Not idling. st->count:1 8,0 1 0 8.347784100 0 m N cfq293A / Not idling. st->count:1 8,0 3 1596 8.354364057 0 C R 156109528 + 8 (6906954) [0] 8,0 3 0 8.354383193 0 m N cfq6196SN / complete rqnoidle 0 8,0 3 0 8.354386476 0 m N cfq schedule dispatch 8,0 3 0 8.354399397 0 m N cfq293A / Not idling. st->count:1 8,0 3 0 8.354404705 0 m N cfq293A / dispatch_insert 8,0 3 0 8.354409454 0 m N cfq293A / dispatched a request 8,0 3 0 8.354412527 0 m N cfq293A / activate rq, drv=1 8,0 3 1597 8.354414692 0 D W 145961400 + 24 (6718452) [swapper/0] 8,0 3 0 8.354484184 0 m N cfq293A / Not idling. st->count:1 8,0 3 0 8.354487536 0 m N cfq293A / slice expired t=0 8,0 3 0 8.354498013 0 m N / served: vt=5888102466265088 min_vt=5888074869387264 8,0 3 0 8.354502692 0 m N cfq293A / sl_used=6737519 disp=1 charge=6737519 iops=0 sect=24 8,0 3 0 8.354505695 0 m N cfq293A / del_from_rr ... 8,0 0 1810 8.354728768 0 C W 145961400 + 24 (314076) [0] 8,0 0 0 8.354746927 0 m N cfq293A / complete rqnoidle 0 ... 8,0 1 3829 8.389886102 5839 G W 145962968 + 24 [kworker/u9:2] 8,0 1 3830 8.389888127 5839 P N [kworker/u9:2] 8,0 1 3831 8.389908102 5839 A W 145978336 + 24 <- (8,4) 44000 8,0 1 3832 8.389910477 5839 Q W 145978336 + 24 [kworker/u9:2] 8,0 1 3833 8.389914248 5839 I W 145962968 + 24 (28146) [kworker/u9:2] 8,0 1 0 8.389919137 0 m N cfq293A / insert_request 8,0 1 0 8.389924305 0 m N cfq293A / add_to_rr 8,0 1 3834 8.389933175 5839 UT N [kworker/u9:2] 1 ... 8,0 0 0 9.455290997 0 m N cfq workload slice:40000000 8,0 0 0 9.455294769 0 m N cfq293A / set_active wl_class:0 wl_type:0 8,0 0 0 9.455303499 0 m N cfq293A / fifo=ffff880003166090 8,0 0 0 9.455306851 0 m N cfq293A / dispatch_insert 8,0 0 0 9.455311251 0 m N cfq293A / dispatched a request 8,0 0 0 9.455314324 0 m N cfq293A / activate rq, drv=1 8,0 0 2043 9.455316210 6204 D W 145962968 + 24 (1065401962) [pgioperf] 8,0 0 0 9.455392407 0 m N cfq293A / Not idling. st->count:1 8,0 0 0 9.455395969 0 m N cfq293A / slice expired t=0 8,0 0 0 9.455404210 0 m N / served: vt=5888958194597888 min_vt=5888941810597888 8,0 0 0 9.455410077 0 m N cfq293A / sl_used=4000000 disp=1 charge=4000000 iops=0 sect=24 8,0 0 0 9.455416851 0 m N cfq293A / del_from_rr ... 8,0 0 2045 9.455648515 0 C W 145962968 + 24 (332305) [0] 8,0 0 0 9.455668350 0 m N cfq293A / complete rqnoidle 0 ... 8,0 1 4371 9.455710115 5839 G W 145978336 + 24 [kworker/u9:2] 8,0 1 4372 9.455712350 5839 P N [kworker/u9:2] 8,0 1 4373 9.455730159 5839 A W 145986616 + 24 <- (8,4) 52280 8,0 1 4374 9.455732674 5839 Q W 145986616 + 24 [kworker/u9:2] 8,0 1 4375 9.455737563 5839 I W 145978336 + 24 (27448) [kworker/u9:2] 8,0 1 0 9.455742871 0 m N cfq293A / insert_request 8,0 1 0 9.455747550 0 m N cfq293A / add_to_rr 8,0 1 4376 9.455756629 5839 UT N [kworker/u9:2] 1 So we can see a Q event for a write request, then IO is blocked by writeback throttling and G and I events for the request happen only once other writeback IO is completed. Thus CFQ always sees only one write request. When it sees it, it queues the async queue behind all the read queues and the async queue gets scheduled after about one second. When it is scheduled, that one request gets dispatched and async queue is expired as it has no more requests to submit. Overall we submit about one write request per second. Although this scheduling is beneficial for read latency, writes are heavily starved and this causes large delays all over the system (due to processes blocking on page lock, transaction starts, etc.). When writeback throttling is disabled, write throughput is about one fifth of a read throughput which roughly matches readers/writers ratio and overall the system stalls are much shorter. Mixing writeback throttling logic with CFQ throttling logic is always a recipe for surprises as CFQ assumes it sees the big part of the picture which is not necessarily true when writeback throttling is blocking requests. So disable writeback throttling logic by default when CFQ is used as an IO scheduler. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar1-0/+1
<linux/sched/clock.h> We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which will have to be picked up from other headers and .c files. Create a trivial placeholder <linux/sched/clock.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-21Merge tag 'for-4.11/linus-merge-signed' of git://git.kernel.dk/linux-blockLinus Torvalds1-5/+9
Pull block layer updates from Jens Axboe: - blk-mq scheduling framework from me and Omar, with a port of the deadline scheduler for this framework. A port of BFQ from Paolo is in the works, and should be ready for 4.12. - Various fixups and improvements to the above scheduling framework from Omar, Paolo, Bart, me, others. - Cleanup of the exported sysfs blk-mq data into debugfs, from Omar. This allows us to export more information that helps debug hangs or performance issues, without cluttering or abusing the sysfs API. - Fixes for the sbitmap code, the scalable bitmap code that was migrated from blk-mq, from Omar. - Removal of the BLOCK_PC support in struct request, and refactoring of carrying SCSI payloads in the block layer. This cleans up the code nicely, and enables us to kill the SCSI specific parts of struct request, shrinking it down nicely. From Christoph mainly, with help from Hannes. - Support for ranged discard requests and discard merging, also from Christoph. - Support for OPAL in the block layer, and for NVMe as well. Mainly from Scott Bauer, with fixes/updates from various others folks. - Error code fixup for gdrom from Christophe. - cciss pci irq allocation cleanup from Christoph. - Making the cdrom device operations read only, from Kees Cook. - Fixes for duplicate bdi registrations and bdi/queue life time problems from Jan and Dan. - Set of fixes and updates for lightnvm, from Matias and Javier. - A few fixes for nbd from Josef, using idr to name devices and a workqueue deadlock fix on receive. Also marks Josef as the current maintainer of nbd. - Fix from Josef, overwriting queue settings when the number of hardware queues is updated for a blk-mq device. - NVMe fix from Keith, ensuring that we don't repeatedly mark and IO aborted, if we didn't end up aborting it. - SG gap merging fix from Ming Lei for block. - Loop fix also from Ming, fixing a race and crash between setting loop status and IO. - Two block race fixes from Tahsin, fixing request list iteration and fixing a race between device registration and udev device add notifiations. - Double free fix from cgroup writeback, from Tejun. - Another double free fix in blkcg, from Hou Tao. - Partition overflow fix for EFI from Alden Tondettar. * tag 'for-4.11/linus-merge-signed' of git://git.kernel.dk/linux-block: (156 commits) nvme: Check for Security send/recv support before issuing commands. block/sed-opal: allocate struct opal_dev dynamically block/sed-opal: tone down not supported warnings block: don't defer flushes on blk-mq + scheduling blk-mq-sched: ask scheduler for work, if we failed dispatching leftovers blk-mq: don't special case flush inserts for blk-mq-sched blk-mq-sched: don't add flushes to the head of requeue queue blk-mq: have blk_mq_dispatch_rq_list() return if we queued IO or not block: do not allow updates through sysfs until registration completes lightnvm: set default lun range when no luns are specified lightnvm: fix off-by-one error on target initialization Maintainers: Modify SED list from nvme to block Move stack parameters for sed_ioctl to prevent oversized stack with CONFIG_KASAN uapi: sed-opal fix IOW for activate lsp to use correct struct cdrom: Make device operations read-only elevator: fix loading wrong elevator type for blk-mq devices cciss: switch to pci_irq_alloc_vectors block/loop: fix race between I/O and set_status blk-mq-sched: don't hold queue_lock when calling exit_icq block: set make_request_fn manually in blk_mq_update_nr_hw_queues ...
2017-02-16cfq-iosched: don't call wbt_disable_default() with IRQs disabledJens Axboe1-12/+13
wbt_disable_default() calls del_timer_sync() to wait for the wbt timer to finish before disabling throttling. We can't do this with IRQs disable. This fixes a lockdep splat on boot, if non-root cgroups are used. Reported-by: Gabriel C <nix.or.die@gmail.com> Fixes: 87760e5eef35 ("block: hook up writeback throttling") Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-08block: enumify ELEVATOR_*_MERGEChristoph Hellwig1-2/+2
Switch these constants to an enum, and make let the compiler ensure that all callers of blk_try_merge and elv_merge handle all potential values. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-23cfq-iosched: Adjust one function call together with a variable assignmentMarkus Elfring1-2/+4
The script "checkpatch.pl" pointed information out like the following. ERROR: do not use assignment in if condition Thus fix the affected source code place. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-23block: Initialize cfqq->ioprio_class in cfq_get_queue()Alexander Potapenko1-0/+2
KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of uninitialized memory in cfq_init_cfqq(): ================================================================== BUG: KMSAN: use of unitialized memory ... Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff8202ac97>] dump_stack+0x157/0x1d0 lib/dump_stack.c:51 [<ffffffff813e9b65>] kmsan_report+0x205/0x360 ??:? [<ffffffff813eabbb>] __msan_warning+0x5b/0xb0 ??:? [< inline >] cfq_init_cfqq block/cfq-iosched.c:3754 [<ffffffff8201e110>] cfq_get_queue+0xc80/0x14d0 block/cfq-iosched.c:3857 ... origin: [<ffffffff8103ab37>] save_stack_trace+0x27/0x50 arch/x86/kernel/stacktrace.c:67 [<ffffffff813e836b>] kmsan_internal_poison_shadow+0xab/0x150 ??:? [<ffffffff813e88ab>] kmsan_poison_slab+0xbb/0x120 ??:? [< inline >] allocate_slab mm/slub.c:1627 [<ffffffff813e533f>] new_slab+0x3af/0x4b0 mm/slub.c:1641 [< inline >] new_slab_objects mm/slub.c:2407 [<ffffffff813e0ef3>] ___slab_alloc+0x323/0x4a0 mm/slub.c:2564 [< inline >] __slab_alloc mm/slub.c:2606 [< inline >] slab_alloc_node mm/slub.c:2669 [<ffffffff813dfb42>] kmem_cache_alloc_node+0x1d2/0x1f0 mm/slub.c:2746 [<ffffffff8201d90d>] cfq_get_queue+0x47d/0x14d0 block/cfq-iosched.c:3850 ... ================================================================== (the line numbers are relative to 4.8-rc6, but the bug persists upstream) The uninitialized struct cfq_queue is created by kmem_cache_alloc_node() and then passed to cfq_init_cfqq(), which accesses cfqq->ioprio_class before it's initialized. Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-17block: move existing elevator ops to unionJens Axboe1-1/+1
Prep patch for adding MQ ops as well, since doing anon unions with named initializers doesn't work on older compilers. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2016-11-28blk-wbt: cleanup disable-by-default for CFQJens Axboe1-6/+3
Make it clear that we are disabling wbt for the specified queued, if it was enabled by default. This is in preparation for allowing users to re-enable wbt, and not have it disabled automatically again. Signed-off-by: Jens Axboe <axboe@fb.com>
2016-11-22block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcgTejun Heo1-1/+2
blkcg allocates some per-cgroup data structures with GFP_NOWAIT and when that fails falls back to operations which aren't specific to the cgroup. Occassional failures are expected under pressure and falling back to non-cgroup operation is the right thing to do. Unfortunately, I forgot to add __GFP_NOWARN to these allocations and these expected failures end up creating a lot of noise. Add __GFP_NOWARN. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Marc MERLIN <marc@merlins.org> Reported-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-11-10block: hook up writeback throttlingJens Axboe1-0/+14
Enable throttling of buffered writeback to make it a lot more smooth, and has way less impact on other system activity. Background writeback should be, by definition, background activity. The fact that we flush huge bundles of it at the time means that it potentially has heavy impacts on foreground workloads, which isn't ideal. We can't easily limit the sizes of writes that we do, since that would impact file system layout in the presence of delayed allocation. So just throttle back buffered writeback, unless someone is waiting for it. The algorithm for when to throttle takes its inspiration in the CoDel networking scheduling algorithm. Like CoDel, blk-wb monitors the minimum latencies of requests over a window of time. In that window of time, if the minimum latency of any request exceeds a given target, then a scale count is incremented and the queue depth is shrunk. The next monitoring window is shrunk accordingly. Unlike CoDel, if we hit a window that exhibits good behavior, then we simply increment the scale count and re-calculate the limits for that scale value. This prevents us from oscillating between a close-to-ideal value and max all the time, instead remaining in the windows where we get good behavior. Unlike CoDel, blk-wb allows the scale count to to negative. This happens if we primarily have writes going on. Unlike positive scale counts, this doesn't change the size of the monitoring window. When the heavy writers finish, blk-bw quickly snaps back to it's stable state of a zero scale count. The patch registers a sysfs entry, 'wb_lat_usec'. This sets the latency target to me met. It defaults to 2 msec for non-rotational storage, and 75 msec for rotational storage. Setting this value to '0' disables blk-wb. Generally, a user would not have to touch this setting. We don't enable WBT on devices that are managed with CFQ, and have a non-root block cgroup attached. If we have a proportional share setup on this particular disk, then the wbt throttling will interfere with that. We don't have a strong need for wbt for that case, since we will rely on CFQ doing that for us. Signed-off-by: Jens Axboe <axboe@fb.com>
2016-11-10block: cfq_cpd_alloc() should use @gfpTejun Heo1-1/+1
cfq_cpd_alloc() which is the cpd_alloc_fn implementation for cfq was incorrectly hard coding GFP_KERNEL instead of using the mask specified through the @gfp parameter. This currently doesn't cause any actual issues because all current callers specify GFP_KERNEL. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Fixes: e4a9bde9589f ("blkcg: replace blkcg_policy->cpd_size with ->cpd_alloc/free_fn() methods") Signed-off-by: Jens Axboe <axboe@fb.com>
2016-11-01block: replace REQ_NOIDLE with REQ_IDLEChristoph Hellwig1-3/+8
Noidle should be the default for writes as seen by all the compounds definitions in fs.h using it. In fact only direct I/O really should be using NODILE, so turn the whole flag around to get the defaults right, which will make our life much easier especially onces the WRITE_* defines go away. This assumes all the existing "raw" users of REQ_SYNC for writes want noidle behavior, which seems to be spot on from a quick audit. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-11-01cfq-iosched: use op_is_sync instead of opencoding itChristoph Hellwig1-12/+4
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-10-28block: better op and flags encodingChristoph Hellwig1-34/+32
Now that we don't need the common flags to overflow outside the range of a 32-bit type we can encode them the same way for both the bio and request fields. This in addition allows us to place the operation first (and make some room for more ops while we're at it) and to stop having to shift around the operation values. In addition this allows passing around only one value in the block layer instead of two (and eventuall also in the file systems, but we can do that later) and thus clean up a lot of code. Last but not least this allows decreasing the size of the cmd_flags field in struct request to 32-bits. Various functions passing this value could also be updated, but I'd like to avoid the churn for now. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-09-23cfq: fix starvation of asynchronous writesGlauber Costa1-3/+10
While debugging timeouts happening in my application workload (ScyllaDB), I have observed calls to open() taking a long time, ranging everywhere from 2 seconds - the first ones that are enough to time out my application - to more than 30 seconds. The problem seems to happen because XFS may block on pending metadata updates under certain circumnstances, and that's confirmed with the following backtrace taken by the offcputime tool (iovisor/bcc): ffffffffb90c57b1 finish_task_switch ffffffffb97dffb5 schedule ffffffffb97e310c schedule_timeout ffffffffb97e1f12 __down ffffffffb90ea821 down ffffffffc046a9dc xfs_buf_lock ffffffffc046abfb _xfs_buf_find ffffffffc046ae4a xfs_buf_get_map ffffffffc046babd xfs_buf_read_map ffffffffc0499931 xfs_trans_read_buf_map ffffffffc044a561 xfs_da_read_buf ffffffffc0451390 xfs_dir3_leaf_read.constprop.16 ffffffffc0452b90 xfs_dir2_leaf_lookup_int ffffffffc0452e0f xfs_dir2_leaf_lookup ffffffffc044d9d3 xfs_dir_lookup ffffffffc047d1d9 xfs_lookup ffffffffc0479e53 xfs_vn_lookup ffffffffb925347a path_openat ffffffffb9254a71 do_filp_open ffffffffb9242a94 do_sys_open ffffffffb9242b9e sys_open ffffffffb97e42b2 entry_SYSCALL_64_fastpath 00007fb0698162ed [unknown] Inspecting my run with blktrace, I can see that the xfsaild kthread exhibit very high "Dispatch wait" times, on the dozens of seconds range and consistent with the open() times I have saw in that run. Still from the blktrace output, we can after searching a bit, identify the request that wasn't dispatched: 8,0 11 152 81.092472813 804 A WM 141698288 + 8 <- (8,1) 141696240 8,0 11 153 81.092472889 804 Q WM 141698288 + 8 [xfsaild/sda1] 8,0 11 154 81.092473207 804 G WM 141698288 + 8 [xfsaild/sda1] 8,0 11 206 81.092496118 804 I WM 141698288 + 8 ( 22911) [xfsaild/sda1] <==== 'I' means Inserted (into the IO scheduler) ===================================> 8,0 0 289372 96.718761435 0 D WM 141698288 + 8 (15626265317) [swapper/0] <==== Only 15s later the CFQ scheduler dispatches the request ======================> As we can see above, in this particular example CFQ took 15 seconds to dispatch this request. Going back to the full trace, we can see that the xfsaild queue had plenty of opportunity to run, and it was selected as the active queue many times. It would just always be preempted by something else (example): 8,0 1 0 81.117912979 0 m N cfq1618SN / insert_request 8,0 1 0 81.117913419 0 m N cfq1618SN / add_to_rr 8,0 1 0 81.117914044 0 m N cfq1618SN / preempt 8,0 1 0 81.117914398 0 m N cfq767A / slice expired t=1 8,0 1 0 81.117914755 0 m N cfq767A / resid=40 8,0 1 0 81.117915340 0 m N / served: vt=1948520448 min_vt=1948520448 8,0 1 0 81.117915858 0 m N cfq767A / sl_used=1 disp=0 charge=0 iops=1 sect=0 where cfq767 is the xfsaild queue and cfq1618 corresponds to one of the ScyllaDB IO dispatchers. The requests preempting the xfsaild queue are synchronous requests. That's a characteristic of ScyllaDB workloads, as we only ever issue O_DIRECT requests. While it can be argued that preempting ASYNC requests in favor of SYNC is part of the CFQ logic, I don't believe that doing so for 15+ seconds is anyone's goal. Moreover, unless I am misunderstanding something, that breaks the expectation set by the "fifo_expire_async" tunable, which in my system is set to the default. Looking at the code, it seems to me that the issue is that after we make an async queue active, there is no guarantee that it will execute any request. When the queue itself tests if it cfq_may_dispatch() it can bail if it sees SYNC requests in flight. An incoming request from another queue can also preempt it in such situation before we have the chance to execute anything (as seen in the trace above). This patch sets the must_dispatch flag if we notice that we have requests that are already fifo_expired. This flag is always cleared after cfq_dispatch_request() returns from cfq_dispatch_requests(), so it won't pin the queue for subsequent requests (unless they are themselves expired) Care is taken during preempt to still allow rt requests to preempt us regardless. Testing my workload with this patch applied produces much better results. From the application side I see no timeouts, and the open() latency histogram generated by systemtap looks much better, with the worst outlier at 131ms: Latency histogram of xfs_buf_lock acquisition (microseconds): value |-------------------------------------------------- count 0 | 11 1 |@@@@ 161 2 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1966 4 |@ 54 8 | 36 16 | 7 32 | 0 64 | 0 ~ 1024 | 0 2048 | 0 4096 | 1 8192 | 1 16384 | 2 32768 | 0 65536 | 0 131072 | 1 262144 | 0 524288 | 0 Signed-off-by: Glauber Costa <glauber@scylladb.com> CC: Jens Axboe <axboe@kernel.dk> CC: linux-block@vger.kernel.org CC: linux-kernel@vger.kernel.org Signed-off-by: Glauber Costa <glauber@scylladb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-08-07block: rename bio bi_rw to bi_opfJens Axboe1-2/+2
Since commit 63a4cc24867d, bio->bi_rw contains flags in the lower portion and the op code in the higher portions. This means that old code that relies on manually setting bi_rw is most likely going to be broken. Instead of letting that brokeness linger, rename the member, to force old and out-of-tree code to break at compile time instead of at runtime. No intended functional changes in this commit. Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-20block: do not merge requests without consulting with io schedulerTahsin Erdogan1-4/+11
Before merging a bio into an existing request, io scheduler is called to get its approval first. However, the requests that come from a plug flush may get merged by block layer without consulting with io scheduler. In case of CFQ, this can cause fairness problems. For instance, if a request gets merged into a low weight cgroup's request, high weight cgroup now will depend on low weight cgroup to get scheduled. If high weigt cgroup needs that io request to complete before submitting more requests, then it will also lose its timeslice. Following script demonstrates the problem. Group g1 has a low weight, g2 and g3 have equal high weights but g2's requests are adjacent to g1's requests so they are subject to merging. Due to these merges, g2 gets poor disk time allocation. cat > cfq-merge-repro.sh << "EOF" #!/bin/bash set -e IO_ROOT=/mnt-cgroup/io mkdir -p $IO_ROOT if ! mount | grep -qw $IO_ROOT; then mount -t cgroup none -oblkio $IO_ROOT fi cd $IO_ROOT for i in g1 g2 g3; do if [ -d $i ]; then rmdir $i fi done mkdir g1 && echo 10 > g1/blkio.weight mkdir g2 && echo 495 > g2/blkio.weight mkdir g3 && echo 495 > g3/blkio.weight RUNTIME=10 (echo $BASHPID > g1/cgroup.procs && fio --readonly --name name1 --filename /dev/sdb \ --rw read --size 64k --bs 64k --time_based \ --runtime=$RUNTIME --offset=0k &> /dev/null)& (echo $BASHPID > g2/cgroup.procs && fio --readonly --name name1 --filename /dev/sdb \ --rw read --size 64k --bs 64k --time_based \ --runtime=$RUNTIME --offset=64k &> /dev/null)& (echo $BASHPID > g3/cgroup.procs && fio --readonly --name name1 --filename /dev/sdb \ --rw read --size 64k --bs 64k --time_based \ --runtime=$RUNTIME --offset=256k &> /dev/null)& sleep $((RUNTIME+1)) for i in g1 g2 g3; do echo ---- $i ---- cat $i/blkio.time done EOF # ./cfq-merge-repro.sh ---- g1 ---- 8:16 162 ---- g2 ---- 8:16 165 ---- g3 ---- 8:16 686 After applying the patch: # ./cfq-merge-repro.sh ---- g1 ---- 8:16 90 ---- g2 ---- 8:16 445 ---- g3 ---- 8:16 471 Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-28cfq-iosched: Charge at least 1 jiffie instead of 1 nsJan Kara1-1/+2
Commit 9a7f38c42c2b (cfq-iosched: Convert from jiffies to nanoseconds) could result in charging just 1 ns to a cgroup submitting IO instead of 1 jiffie we always charged before. It is arguable what is the right amount to change but for now lets retain the old behavior of always charging at least one jiffie. Fixes: 9a7f38c42c2b92391d9dabaf9f51df7cfe5608e4 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-28cfq-iosched: Fix regression in bonnie++ rewrite performanceJan Kara1-1/+10
Commit 9a7f38c42c2 (cfq-iosched: Convert from jiffies to nanoseconds) broke the condition for detecting starved sync IO in cfq_completed_request() because rq->start_time remained in jiffies but we compared it with nanosecond values. This manifested as a regression in bonnie++ rewrite performance because we always ended up considering sync IO starved and thus never increased async IO queue depth. Since rq->start_time is used in a lot of places, converting it to ns values would be non-trivial. So just revert the condition in CFQ to use comparison with jiffies. This will lead to suboptimal results if cfq_fifo_expire[1] will ever come close to 1 jiffie but so far we are relatively far from that with the storage used with CFQ (the default value is 128 ms). Fixes: 9a7f38c42c2b92391d9dabaf9f51df7cfe5608e4 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-28cfq-iosched: Convert slice_resid from u64 to s64Jan Kara1-2/+2
slice_resid can be both positive and negative. Commit 9a7f38c42c2b (cfq-iosched: Convert from jiffies to nanoseconds) converted it from long to u64. Although this did not introduce any functional regression (the operations just overflow and the result was fine), it is certainly wrong and could cause issues in future. So convert the type to more appropriate s64. Fixes: 9a7f38c42c2b92391d9dabaf9f51df7cfe5608e4 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-09cfq-iosched: temporarily boost queue priority for idle classesJens Axboe1-1/+21
If we're queuing REQ_PRIO IO and the task is running at an idle IO class, then temporarily boost the priority. This prevents livelocks due to priority inversion, when a low priority task is holding file system resources while attempting to do IO. An example of that is shown below. An ioniced idle task is holding the directory mutex, while a normal priority task is trying to do a directory lookup. [478381.198925] ------------[ cut here ]------------ [478381.200315] INFO: task ionice:1168369 blocked for more than 120 seconds. [478381.201324] Not tainted 4.0.9-38_fbk5_hotfix1_2936_g85409c6 #1 [478381.202278] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [478381.203462] ionice D ffff8803692736a8 0 1168369 1 0x00000080 [478381.203466] ffff8803692736a8 ffff880399c21300 ffff880276adcc00 ffff880369273698 [478381.204589] ffff880369273fd8 0000000000000000 7fffffffffffffff 0000000000000002 [478381.205752] ffffffff8177d5e0 ffff8803692736c8 ffffffff8177cea7 0000000000000000 [478381.206874] Call Trace: [478381.207253] [<ffffffff8177d5e0>] ? bit_wait_io_timeout+0x80/0x80 [478381.208175] [<ffffffff8177cea7>] schedule+0x37/0x90 [478381.208932] [<ffffffff8177f5fc>] schedule_timeout+0x1dc/0x250 [478381.209805] [<ffffffff81421c17>] ? __blk_run_queue+0x37/0x50 [478381.210706] [<ffffffff810ca1c5>] ? ktime_get+0x45/0xb0 [478381.211489] [<ffffffff8177c407>] io_schedule_timeout+0xa7/0x110 [478381.212402] [<ffffffff810a8c2b>] ? prepare_to_wait+0x5b/0x90 [478381.213280] [<ffffffff8177d616>] bit_wait_io+0x36/0x50 [478381.214063] [<ffffffff8177d325>] __wait_on_bit+0x65/0x90 [478381.214961] [<ffffffff8177d5e0>] ? bit_wait_io_timeout+0x80/0x80 [478381.215872] [<ffffffff8177d47c>] out_of_line_wait_on_bit+0x7c/0x90 [478381.216806] [<ffffffff810a89f0>] ? wake_atomic_t_function+0x40/0x40 [478381.217773] [<ffffffff811f03aa>] __wait_on_buffer+0x2a/0x30 [478381.218641] [<ffffffff8123c557>] ext4_bread+0x57/0x70 [478381.219425] [<ffffffff8124498c>] __ext4_read_dirblock+0x3c/0x380 [478381.220467] [<ffffffff8124665d>] ext4_dx_find_entry+0x7d/0x170 [478381.221357] [<ffffffff8114c49e>] ? find_get_entry+0x1e/0xa0 [478381.222208] [<ffffffff81246bd4>] ext4_find_entry+0x484/0x510 [478381.223090] [<ffffffff812471a2>] ext4_lookup+0x52/0x160 [478381.223882] [<ffffffff811c401d>] lookup_real+0x1d/0x60 [478381.224675] [<ffffffff811c4698>] __lookup_hash+0x38/0x50 [478381.225697] [<ffffffff817745bd>] lookup_slow+0x45/0xab [478381.226941] [<ffffffff811c690e>] link_path_walk+0x7ae/0x820 [478381.227880] [<ffffffff811c6a42>] path_init+0xc2/0x430 [478381.228677] [<ffffffff813e6e26>] ? security_file_alloc+0x16/0x20 [478381.229776] [<ffffffff811c8c57>] path_openat+0x77/0x620 [478381.230767] [<ffffffff81185c6e>] ? page_add_file_rmap+0x2e/0x70 [478381.232019] [<ffffffff811cb253>] do_filp_open+0x43/0xa0 [478381.233016] [<ffffffff8108c4a9>] ? creds_are_invalid+0x29/0x70 [478381.234072] [<ffffffff811c0cb0>] do_open_execat+0x70/0x170 [478381.235039] [<ffffffff811c1bf8>] do_execveat_common.isra.36+0x1b8/0x6e0 [478381.236051] [<ffffffff811c214c>] do_execve+0x2c/0x30 [478381.236809] [<ffffffff811ca392>] ? getname+0x12/0x20 [478381.237564] [<ffffffff811c23be>] SyS_execve+0x2e/0x40 [478381.238338] [<ffffffff81780a1d>] stub_execve+0x6d/0xa0 [478381.239126] ------------[ cut here ]------------ [478381.239915] ------------[ cut here ]------------ [478381.240606] INFO: task python2.7:1168375 blocked for more than 120 seconds. [478381.242673] Not tainted 4.0.9-38_fbk5_hotfix1_2936_g85409c6 #1 [478381.243653] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [478381.244902] python2.7 D ffff88005cf8fb98 0 1168375 1168248 0x00000080 [478381.244904] ffff88005cf8fb98 ffff88016c1f0980 ffffffff81c134c0 ffff88016c1f11a0 [478381.246023] ffff88005cf8ffd8 ffff880466cd0cbc ffff88016c1f0980 00000000ffffffff [478381.247138] ffff880466cd0cc0 ffff88005cf8fbb8 ffffffff8177cea7 ffff88005cf8fcc8 [478381.248252] Call Trace: [478381.248630] [<ffffffff8177cea7>] schedule+0x37/0x90 [478381.249382] [<ffffffff8177d08e>] schedule_preempt_disabled+0xe/0x10 [478381.250465] [<ffffffff8177e892>] __mutex_lock_slowpath+0x92/0x100 [478381.251409] [<ffffffff8177e91b>] mutex_lock+0x1b/0x2f [478381.252199] [<ffffffff817745ae>] lookup_slow+0x36/0xab [478381.253023] [<ffffffff811c690e>] link_path_walk+0x7ae/0x820 [478381.253877] [<ffffffff811aeb41>] ? try_charge+0xc1/0x700 [478381.254690] [<ffffffff811c6a42>] path_init+0xc2/0x430 [478381.255525] [<ffffffff813e6e26>] ? security_file_alloc+0x16/0x20 [478381.256450] [<ffffffff811c8c57>] path_openat+0x77/0x620 [478381.257256] [<ffffffff8115b2fb>] ? lru_cache_add_active_or_unevictable+0x2b/0xa0 [478381.258390] [<ffffffff8117b623>] ? handle_mm_fault+0x13f3/0x1720 [478381.259309] [<ffffffff811cb253>] do_filp_open+0x43/0xa0 [478381.260139] [<ffffffff811d7ae2>] ? __alloc_fd+0x42/0x120 [478381.260962] [<ffffffff811b95ac>] do_sys_open+0x13c/0x230 [478381.261779] [<ffffffff81011393>] ? syscall_trace_enter_phase1+0x113/0x170 [478381.262851] [<ffffffff811b96c2>] SyS_open+0x22/0x30 [478381.263598] [<ffffffff81780532>] system_call_fastpath+0x12/0x17 [478381.264551] ------------[ cut here ]------------ [478381.265377] ------------[ cut here ]------------ Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
2016-06-08cfq-iosched: Convert to use highres timersJan Kara1-9/+12
Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-08cfq-iosched: Expose microsecond interfacesJeff Moyer1-0/+40
Expose interfaces to tune time slices of CFQ IO scheduler in microseconds. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-08cfq-iosched: Convert from jiffies to nanosecondsJeff Moyer1-137/+136
Convert all time-keeping in CFQ IO scheduler from jiffies to nanoseconds so that we can later make the intervals more fine-grained than jiffies. One jiffie is several miliseconds and even for today's rotating disks that is a noticeable amount of time and thus we leave disk unnecessarily idle. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-07block: convert is_sync helpers to use REQ_OPs.Mike Christie1-1/+1
This patch converts the is_sync helpers to use separate variables for the operation and flags. Signed-off-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-07blkg_rwstat: separate op from flagsMike Christie1-20/+29
The bio and request operation and flags are going to be separate definitions, so we cannot pass them in as a bitmap. This patch converts the blkg_rwstat code and its caller, cfq, to pass in the values separately. Signed-off-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-07block: prepare elevator to use REQ_OPs.Mike Christie1-2/+2
This patch converts the elevator code to use separate variables for the operation and flags, and to check req_op for the REQ_OP. Signed-off-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-04-04mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macrosKirill A. Shutemov1-1/+1
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-04cfq-iosched: Allow parent cgroup to preempt its childJan Kara1-1/+18
Currently we don't allow sync workload of one cgroup to preempt sync workload of any other cgroup. This is because we want to achieve service separation between cgroups. However in cases where cgroup preempting is ancestor of the current cgroup, there is no need of separation and idling introduces unnecessary overhead. This hurts for example the case when workload is isolated within a cgroup but journalling threads are in root cgroup. Simple way to demostrate the issue is using: dbench4 -c /usr/share/dbench4/client.txt -t 10 -D /mnt 1 on ext4 filesystem on plain SATA drive (mounted with barrier=0 to make difference more visible). When all processes are in the root cgroup, reported throughput is 153.132 MB/sec. When dbench process gets its own blkio cgroup, reported throughput drops to 26.1006 MB/sec. Fix the problem by making check in cfq_should_preempt() more benevolent and allow preemption by ancestor cgroup. This improves the throughput reported by dbench4 to 48.9106 MB/sec. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-02-04cfq-iosched: Allow sync noidle workloads to preempt each otherJan Kara1-1/+0
The original idea with preemption of sync noidle queues (introduced in commit 718eee0579b8 "cfq-iosched: fairness for sync no-idle queues") was that we service all sync noidle queues together, we don't idle on any of the queues individually and we idle only if there is no sync noidle queue to be served. This intention also matches the original test: if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && new_cfqq->service_tree == cfqq->service_tree) return true; However since at that time cfqq->service_tree was not set for idling queues, this test was unreliable and was replaced in commit e4a229196a7c "cfq-iosched: fix no-idle preemption logic" by: if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && new_cfqq->service_tree->count == 1) return true; That was a reliable test but was actually doing something different - now we preempt sync noidle queue only if the new queue is the only one busy in the service tree. These days cfq queue is kept in service tree even if it is idling and thus the original check would be safe again. But since we actually check that cfq queues are in the same cgroup, of the same priority class and workload type (sync noidle), we know that new_cfqq is fine to preempt cfqq. So just remove the service tree check. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-02-04cfq-iosched: Reorder checks in cfq_should_preempt()Jan Kara1-6/+7
Move check for preemption by rt class up. There is no functional change but it makes arguing about conditions simpler since we can be sure both cfq queues are from the same ioprio class. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-02-04cfq-iosched: Don't group_idle if cfqq has big thinktimeJan Kara1-2/+8
There is no point in idling on a cfq group if the only cfq queue that is there has too big thinktime. Signed-off-by: Jan Kara <jack@suse.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-09-18cgroup: replace cgroup_on_dfl() tests in controllers with cgroup_subsys_on_dfl()Tejun Heo1-2/+2
cgroup_on_dfl() tests whether the cgroup's root is the default hierarchy; however, an individual controller is only interested in whether the controller is attached to the default hierarchy and never tests a cgroup which doesn't belong to the hierarchy that the controller is attached to. This patch replaces cgroup_on_dfl() tests in controllers with faster static_key based cgroup_subsys_on_dfl(). This leaves cgroup core as the only user of cgroup_on_dfl() and the function is moved from the header file to cgroup.c. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org>
2015-08-18blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchyTejun Heo1-15/+40
cgroup is trying to make interface consistent across different controllers. For weight based resource control, the knob should have the range [1, 10000] and default to 100. This patch updates cfq-iosched so that the weight range conforms. The internal calculations have enough range and the widening of the weight range shouldn't cause any problem. * blkcg_policy->cpd_bind_fn() is added. If present, this is invoked when blkcg is attached to a hierarchy. * cfq_cpd_init() is updated to use the new default value on the unified hierarchy. * cfq_cpd_bind() callback is implemented to clear per-blkg configs and apply the default config matching the hierarchy type. * cfqd->root_group->[leaf_]weight initialization in cfq_init_queue() is moved into !CONFIG_CFQ_GROUP_IOSCHED block. cfq_cpd_bind() is now responsible for initializing the initial weights when blkcg is enabled. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: s/CFQ_WEIGHT_*/CFQ_WEIGHT_LEGACY_*/Tejun Heo1-11/+11
blkcg is gonna switch to cgroup common weight range as defined by CGROUP_WEIGHT_* on the unified hierarchy. In preparation, rename CFQ_WEIGHT_* constants to CFQ_WEIGHT_LEGACY_*. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: implement interface for the unified hierarchyTejun Heo1-5/+56
blkcg interface grew to be the biggest of all controllers and unfortunately most inconsistent too. The interface files are inconsistent with a number of cloes duplicates. Some files have recursive variants while others don't. There's distinction between normal and leaf weights which isn't intuitive and there are a lot of stat knobs which don't make much sense outside of debugging and expose too much implementation details to userland. In the unified hierarchy, everything is always hierarchical and internal nodes can't have tasks rendering the two structural issues twisting the current interface. The interface has to be updated in a significant anyway and this is a good chance to revamp it as a whole. This patch implements blkcg interface for the unified hierarchy. * (from a previous patch) blkcg is identified by "io" instead of "blkio" on the unified hierarchy. Given that the whole interface is updated anyway, the rename shouldn't carry noticeable conversion overhead. * The original interface consisted of 27 files is replaced with the following three files. blkio.stat : per-blkcg stats blkio.weight : per-cgroup and per-cgroup-queue weight settings blkio.max : per-cgroup-queue bps and iops max limits Documentation/cgroups/unified-hierarchy.txt updated accordingly. v2: blkcg_policy->dfl_cftypes wasn't removed on blkcg_policy_unregister() corrupting the cftypes list. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: misc preparations for unified hierarchy interfaceTejun Heo1-4/+4
* Export blkg_dev_name() * Drop unnecessary @cft from __cfq_set_weight(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: move body parsing from blkg_conf_prep() to its callersTejun Heo1-6/+11
Currently, blkg_conf_prep() expects input to be of the following form MAJ:MIN NUM and reads the NUM part into blkg_conf_ctx->v. This is quite restrictive and gets in the way in implementing blkcg interface for the unified hierarchy. This patch updates blkg_conf_prep() so that it expects MAJ:MIN BODY_STR where BODY_STR is an arbitrary string. blkg_conf_ctx->v is replaced with ->body which is a char pointer pointing to the start of BODY_STR. Parsing of the body is moved to blkg_conf_prep()'s callers. To allow using, for example, strsep() on blkg_conf_ctx->val, it is a non-const pointer and to accommodate that const is dropped from @input too. This doesn't cause any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: mark existing cftypes as legacyTejun Heo1-2/+2
blkcg is about to grow interface for the unified hierarchy. Add legacy to existing cftypes. * blkcg_policy->cftypes -> blkcg_policy->legacy_cftypes * blk-cgroup.c:blkcg_files -> blkcg_legacy_files * cfq-iosched.c:cfq_blkcg_files -> cfq_blkcg_legacy_files * blk-throttle.c:throtl_files -> throtl_legacy_files Pure renames. No functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: refine error codes returned during blkcg configurationTejun Heo1-1/+1
blkcg currently returns -EINVAL for most errors which can be pretty confusing given that the failure modes are quite varied. Update the error returns so that * -EINVAL only for syntactic errors. * -ERANGE if the value is out of range. * -ENODEV if the target device can't be found. * -EOPNOTSUPP if the policy is not enabled on the target device. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-18blkcg: remove unnecessary NULL checks from __cfqg_set_weight_device()Tejun Heo1-4/+1
blkg_to_cfqg() and blkcg_to_cfqgd() on a valid blkg with the policy enabled are guaranteed to return non-NULL and the counterpart in blk-throttle doesn't have these checks either. Remove the spurious NULL checks. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-17 12:54:10 +0000