diff options
Diffstat (limited to 'Documentation/block')
| -rw-r--r-- | Documentation/block/bfq-iosched.txt | 12 | ||||
| -rw-r--r-- | Documentation/block/biodoc.txt | 1 | ||||
| -rw-r--r-- | Documentation/block/queue-sysfs.txt | 64 |
3 files changed, 49 insertions, 28 deletions
diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt index b2265cf6c9c3..bbd6eb5bbb07 100644 --- a/Documentation/block/bfq-iosched.txt +++ b/Documentation/block/bfq-iosched.txt @@ -38,13 +38,13 @@ stack). To give an idea of the limits with BFQ, on slow or average CPUs, here are, first, the limits of BFQ for three different CPUs, on, respectively, an average laptop, an old desktop, and a cheap embedded system, in case full hierarchical support is enabled (i.e., -CONFIG_BFQ_GROUP_IOSCHED is set), but CONFIG_DEBUG_BLK_CGROUP is not +CONFIG_BFQ_GROUP_IOSCHED is set), but CONFIG_BFQ_CGROUP_DEBUG is not set (Section 4-2): - Intel i7-4850HQ: 400 KIOPS - AMD A8-3850: 250 KIOPS - ARM CortexTM-A53 Octa-core: 80 KIOPS -If CONFIG_DEBUG_BLK_CGROUP is set (and of course full hierarchical +If CONFIG_BFQ_CGROUP_DEBUG is set (and of course full hierarchical support is enabled), then the sustainable throughput with BFQ decreases, because all blkio.bfq* statistics are created and updated (Section 4-2). For BFQ, this leads to the following maximum @@ -537,19 +537,19 @@ or io.bfq.weight. As for cgroups-v1 (blkio controller), the exact set of stat files created, and kept up-to-date by bfq, depends on whether -CONFIG_DEBUG_BLK_CGROUP is set. If it is set, then bfq creates all +CONFIG_BFQ_CGROUP_DEBUG is set. If it is set, then bfq creates all the stat files documented in Documentation/cgroup-v1/blkio-controller.rst. If, instead, -CONFIG_DEBUG_BLK_CGROUP is not set, then bfq creates only the files +CONFIG_BFQ_CGROUP_DEBUG is not set, then bfq creates only the files blkio.bfq.io_service_bytes blkio.bfq.io_service_bytes_recursive blkio.bfq.io_serviced blkio.bfq.io_serviced_recursive -The value of CONFIG_DEBUG_BLK_CGROUP greatly influences the maximum +The value of CONFIG_BFQ_CGROUP_DEBUG greatly influences the maximum throughput sustainable with bfq, because updating the blkio.bfq.* stats is rather costly, especially for some of the stats enabled by -CONFIG_DEBUG_BLK_CGROUP. +CONFIG_BFQ_CGROUP_DEBUG. Parameters to set ----------------- diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index ac18b488cb5e..31c177663ed5 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -436,7 +436,6 @@ struct bio { struct bvec_iter bi_iter; /* current index into bio_vec array */ unsigned int bi_size; /* total size in bytes */ - unsigned short bi_phys_segments; /* segments after physaddr coalesce*/ unsigned short bi_hw_segments; /* segments after DMA remapping */ unsigned int bi_max; /* max bio_vecs we can hold used as index into pool */ diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index 83b457e24bba..b40b5b7cebd9 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -14,6 +14,15 @@ add_random (RW) This file allows to turn off the disk entropy contribution. Default value of this file is '1'(on). +chunk_sectors (RO) +------------------ +This has different meaning depending on the type of the block device. +For a RAID device (dm-raid), chunk_sectors indicates the size in 512B sectors +of the RAID volume stripe segment. For a zoned block device, either host-aware +or host-managed, chunk_sectors indicates the size in 512B sectors of the zones +of the device, with the eventual exception of the last zone of the device which +may be smaller. + dax (RO) -------- This file indicates whether the device supports Direct Access (DAX), @@ -43,6 +52,16 @@ large discards are issued, setting this value lower will make Linux issue smaller discards and potentially help reduce latencies induced by large discard operations. +discard_zeroes_data (RO) +------------------------ +Obsolete. Always zero. + +fua (RO) +-------- +Whether or not the block driver supports the FUA flag for write requests. +FUA stands for Force Unit Access. If the FUA flag is set that means that +write requests must bypass the volatile cache of the storage device. + hw_sector_size (RO) ------------------- This is the hardware sector size of the device, in bytes. @@ -83,14 +102,19 @@ logical_block_size (RO) ----------------------- This is the logical block size of the device, in bytes. +max_discard_segments (RO) +------------------------- +The maximum number of DMA scatter/gather entries in a discard request. + max_hw_sectors_kb (RO) ---------------------- This is the maximum number of kilobytes supported in a single data transfer. max_integrity_segments (RO) --------------------------- -When read, this file shows the max limit of integrity segments as -set by block layer which a hardware controller can handle. +Maximum number of elements in a DMA scatter/gather list with integrity +data that will be submitted by the block layer core to the associated +block driver. max_sectors_kb (RW) ------------------- @@ -100,11 +124,12 @@ size allowed by the hardware. max_segments (RO) ----------------- -Maximum number of segments of the device. +Maximum number of elements in a DMA scatter/gather list that is submitted +to the associated block driver. max_segment_size (RO) --------------------- -Maximum segment size of the device. +Maximum size in bytes of a single element in a DMA scatter/gather list. minimum_io_size (RO) -------------------- @@ -132,6 +157,12 @@ per-block-cgroup request pool. IOW, if there are N block cgroups, each request queue may have up to N request pools, each independently regulated by nr_requests. +nr_zones (RO) +------------- +For zoned block devices (zoned attribute indicating "host-managed" or +"host-aware"), this indicates the total number of zones of the device. +This is always 0 for regular block devices. + optimal_io_size (RO) -------------------- This is the optimal IO size reported by the device. @@ -185,8 +216,8 @@ This is the number of bytes the device can write in a single write-same command. A value of '0' means write-same is not supported by this device. -wb_lat_usec (RW) ----------------- +wbt_lat_usec (RW) +----------------- If the device is registered for writeback throttling, then this file shows the target minimum read latency. If this latency is exceeded in a given window of time (see wb_window_usec), then the writeback throttling will start @@ -201,6 +232,12 @@ blk-throttle makes decision based on the samplings. Lower time means cgroups have more smooth throughput, but higher CPU overhead. This exists only when CONFIG_BLK_DEV_THROTTLING_LOW is enabled. +write_zeroes_max_bytes (RO) +--------------------------- +For block drivers that support REQ_OP_WRITE_ZEROES, the maximum number of +bytes that can be zeroed at once. The value 0 means that REQ_OP_WRITE_ZEROES +is not supported. + zoned (RO) ---------- This indicates if the device is a zoned block device and the zone model of the @@ -213,19 +250,4 @@ devices are described in the ZBC (Zoned Block Commands) and ZAC do not support zone commands, they will be treated as regular block devices and zoned will report "none". -nr_zones (RO) -------------- -For zoned block devices (zoned attribute indicating "host-managed" or -"host-aware"), this indicates the total number of zones of the device. -This is always 0 for regular block devices. - -chunk_sectors (RO) ------------------- -This has different meaning depending on the type of the block device. -For a RAID device (dm-raid), chunk_sectors indicates the size in 512B sectors -of the RAID volume stripe segment. For a zoned block device, either host-aware -or host-managed, chunk_sectors indicates the size in 512B sectors of the zones -of the device, with the eventual exception of the last zone of the device which -may be smaller. - Jens Axboe <jens.axboe@oracle.com>, February 2009 |