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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-16 21:33:35 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-16 21:33:35 +0100 |
commit | 005b2a9dc819a1265a8c765595f8f6d88d6173d9 (patch) | |
tree | 688107572f6b3e017fc7ccf54f552c6a30441a79 /arch/nios2 | |
parent | Merge branch 'parisc-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git... (diff) | |
parent | io_uring: remove 'twa_signal_ok' deadlock work-around (diff) | |
download | linux-005b2a9dc819a1265a8c765595f8f6d88d6173d9.tar.xz linux-005b2a9dc819a1265a8c765595f8f6d88d6173d9.zip |
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/nios2')
-rw-r--r-- | arch/nios2/include/asm/thread_info.h | 2 | ||||
-rw-r--r-- | arch/nios2/kernel/signal.c | 3 |
2 files changed, 4 insertions, 1 deletions
diff --git a/arch/nios2/include/asm/thread_info.h b/arch/nios2/include/asm/thread_info.h index 7349a4fa635b..272d2c72a727 100644 --- a/arch/nios2/include/asm/thread_info.h +++ b/arch/nios2/include/asm/thread_info.h @@ -86,6 +86,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_MEMDIE 4 /* is terminating due to OOM killer */ #define TIF_SECCOMP 5 /* secure computing */ #define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */ +#define TIF_NOTIFY_SIGNAL 7 /* signal notifications exist */ #define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */ #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling @@ -97,6 +98,7 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) +#define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) #define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK) #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) diff --git a/arch/nios2/kernel/signal.c b/arch/nios2/kernel/signal.c index cf2dca2ac7c3..2009ae2d3c3b 100644 --- a/arch/nios2/kernel/signal.c +++ b/arch/nios2/kernel/signal.c @@ -306,7 +306,8 @@ asmlinkage int do_notify_resume(struct pt_regs *regs) if (!user_mode(regs)) return 0; - if (test_thread_flag(TIF_SIGPENDING)) { + if (test_thread_flag(TIF_SIGPENDING) || + test_thread_flag(TIF_NOTIFY_SIGNAL)) { int restart = do_signal(regs); if (unlikely(restart)) { |