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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-16 12:33:35 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-16 12:33:35 -0800 |
commit | 005b2a9dc819a1265a8c765595f8f6d88d6173d9 (patch) | |
tree | 688107572f6b3e017fc7ccf54f552c6a30441a79 /arch/sparc/include | |
parent | 5ee863bec794f30bdf7fdf57ce0d9f579b0d1aa3 (diff) | |
parent | 355fb9e2b78e78b38ec00f5cd9b05c6aceb98335 (diff) | |
download | linux-005b2a9dc819a1265a8c765595f8f6d88d6173d9.tar.bz2 |
Merge tag 'tif-task_work.arch-2020-12-14' of git://git.kernel.dk/linux-block
Pull TIF_NOTIFY_SIGNAL updates from Jens Axboe:
"This sits on top of of the core entry/exit and x86 entry branch from
the tip tree, which contains the generic and x86 parts of this work.
Here we convert the rest of the archs to support TIF_NOTIFY_SIGNAL.
With that done, we can get rid of JOBCTL_TASK_WORK from task_work and
signal.c, and also remove a deadlock work-around in io_uring around
knowing that signal based task_work waking is invoked with the sighand
wait queue head lock.
The motivation for this work is to decouple signal notify based
task_work, of which io_uring is a heavy user of, from sighand. The
sighand lock becomes a huge contention point, particularly for
threaded workloads where it's shared between threads. Even outside of
threaded applications it's slower than it needs to be.
Roman Gershman <romger@amazon.com> reported that his networked
workload dropped from 1.6M QPS at 80% CPU to 1.0M QPS at 100% CPU
after io_uring was changed to use TIF_NOTIFY_SIGNAL. The time was all
spent hammering on the sighand lock, showing 57% of the CPU time there
[1].
There are further cleanups possible on top of this. One example is
TIF_PATCH_PENDING, where a patch already exists to use
TIF_NOTIFY_SIGNAL instead. Hopefully this will also lead to more
consolidation, but the work stands on its own as well"
[1] https://github.com/axboe/liburing/issues/215
* tag 'tif-task_work.arch-2020-12-14' of git://git.kernel.dk/linux-block: (28 commits)
io_uring: remove 'twa_signal_ok' deadlock work-around
kernel: remove checking for TIF_NOTIFY_SIGNAL
signal: kill JOBCTL_TASK_WORK
io_uring: JOBCTL_TASK_WORK is no longer used by task_work
task_work: remove legacy TWA_SIGNAL path
sparc: add support for TIF_NOTIFY_SIGNAL
riscv: add support for TIF_NOTIFY_SIGNAL
nds32: add support for TIF_NOTIFY_SIGNAL
ia64: add support for TIF_NOTIFY_SIGNAL
h8300: add support for TIF_NOTIFY_SIGNAL
c6x: add support for TIF_NOTIFY_SIGNAL
alpha: add support for TIF_NOTIFY_SIGNAL
xtensa: add support for TIF_NOTIFY_SIGNAL
arm: add support for TIF_NOTIFY_SIGNAL
microblaze: add support for TIF_NOTIFY_SIGNAL
hexagon: add support for TIF_NOTIFY_SIGNAL
csky: add support for TIF_NOTIFY_SIGNAL
openrisc: add support for TIF_NOTIFY_SIGNAL
sh: add support for TIF_NOTIFY_SIGNAL
um: add support for TIF_NOTIFY_SIGNAL
...
Diffstat (limited to 'arch/sparc/include')
-rw-r--r-- | arch/sparc/include/asm/thread_info_32.h | 4 | ||||
-rw-r--r-- | arch/sparc/include/asm/thread_info_64.h | 6 |
2 files changed, 7 insertions, 3 deletions
diff --git a/arch/sparc/include/asm/thread_info_32.h b/arch/sparc/include/asm/thread_info_32.h index 548b366165dd..45b4955b253f 100644 --- a/arch/sparc/include/asm/thread_info_32.h +++ b/arch/sparc/include/asm/thread_info_32.h @@ -104,6 +104,7 @@ register struct thread_info *current_thread_info_reg asm("g6"); #define TIF_SIGPENDING 2 /* signal pending */ #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ #define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */ +#define TIF_NOTIFY_SIGNAL 5 /* signal notifications exist */ #define TIF_USEDFPU 8 /* FPU was used by this task * this quantum (SMP) */ #define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling @@ -115,11 +116,12 @@ register struct thread_info *current_thread_info_reg asm("g6"); #define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME) #define _TIF_SIGPENDING (1<<TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED) +#define _TIF_NOTIFY_SIGNAL (1<<TIF_NOTIFY_SIGNAL) #define _TIF_USEDFPU (1<<TIF_USEDFPU) #define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG) #define _TIF_DO_NOTIFY_RESUME_MASK (_TIF_NOTIFY_RESUME | \ - _TIF_SIGPENDING) + _TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL) #define is_32bit_task() (1) diff --git a/arch/sparc/include/asm/thread_info_64.h b/arch/sparc/include/asm/thread_info_64.h index 20255471e653..42cd4cd3892e 100644 --- a/arch/sparc/include/asm/thread_info_64.h +++ b/arch/sparc/include/asm/thread_info_64.h @@ -180,7 +180,7 @@ extern struct thread_info *current_thread_info(void); #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ #define TIF_SIGPENDING 2 /* signal pending */ #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ -/* flag bit 4 is available */ +#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */ #define TIF_UNALIGNED 5 /* allowed to do unaligned accesses */ #define TIF_UPROBE 6 /* breakpointed or singlestepped */ #define TIF_32BIT 7 /* 32-bit binary */ @@ -200,6 +200,7 @@ extern struct thread_info *current_thread_info(void); #define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME) #define _TIF_SIGPENDING (1<<TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED) +#define _TIF_NOTIFY_SIGNAL (1<<TIF_NOTIFY_SIGNAL) #define _TIF_UNALIGNED (1<<TIF_UNALIGNED) #define _TIF_UPROBE (1<<TIF_UPROBE) #define _TIF_32BIT (1<<TIF_32BIT) @@ -213,7 +214,8 @@ extern struct thread_info *current_thread_info(void); _TIF_DO_NOTIFY_RESUME_MASK | \ _TIF_NEED_RESCHED) #define _TIF_DO_NOTIFY_RESUME_MASK (_TIF_NOTIFY_RESUME | \ - _TIF_SIGPENDING | _TIF_UPROBE) + _TIF_SIGPENDING | _TIF_UPROBE | \ + _TIF_NOTIFY_SIGNAL) #define is_32bit_task() (test_thread_flag(TIF_32BIT)) |