diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-16 12:33:35 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-16 12:33:35 -0800 |
| commit | 005b2a9dc819a1265a8c765595f8f6d88d6173d9 (patch) | |
| tree | 688107572f6b3e017fc7ccf54f552c6a30441a79 /include/linux/entry-common.h | |
| parent | 5ee863bec794f30bdf7fdf57ce0d9f579b0d1aa3 (diff) | |
| parent | 355fb9e2b78e78b38ec00f5cd9b05c6aceb98335 (diff) | |
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 'include/linux/entry-common.h')
| -rw-r--r-- | include/linux/entry-common.h | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 7c581a4c3797..ca86a00abe86 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -21,10 +21,6 @@ # define _TIF_UPROBE (0) #endif -#ifndef _TIF_NOTIFY_SIGNAL -# define _TIF_NOTIFY_SIGNAL (0) -#endif - /* * SYSCALL_WORK flags handled in syscall_enter_from_user_mode() */ |