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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-14 14:17:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-14 14:17:51 -0700
commitb6b178e38f40f34842b719a8786d346d4cfec5dc (patch)
treeea3bc78256ba54ab96a74e1b6dc5f9ab3fd044e2 /arch/x86
parent1d229a65b419cf51a9921d73907f1998a0e14daa (diff)
parent0099808553ad4f9c04ad7afd966f6d7f470f247f (diff)
Merge tag 'timers-core-2020-08-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull more timer updates from Thomas Gleixner: "A set of posix CPU timer changes which allows to defer the heavy work of posix CPU timers into task work context. The tick interrupt is reduced to a quick check which queues the work which is doing the heavy lifting before returning to user space or going back to guest mode. Moving this out is deferring the signal delivery slightly but posix CPU timers are inaccurate by nature as they depend on the tick so there is no real damage. The relevant test cases all passed. This lifts the last offender for RT out of the hard interrupt context tick handler, but it also has the general benefit that the actual heavy work is accounted to the task/process and not to the tick interrupt itself. Further optimizations are possible to break long sighand lock hold and interrupt disabled (on !RT kernels) times when a massive amount of posix CPU timers (which are unpriviledged) is armed for a task/process. This is currently only enabled for x86 because the architecture has to ensure that task work is handled in KVM before entering a guest, which was just established for x86 with the new common entry/exit code which got merged post 5.8 and is not the case for other KVM architectures" * tag 'timers-core-2020-08-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86: Select POSIX_CPU_TIMERS_TASK_WORK posix-cpu-timers: Provide mechanisms to defer timer handling to task_work posix-cpu-timers: Split run_posix_cpu_timers()
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9a2849527dd7..7101ac64bb20 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -209,6 +209,7 @@ config X86
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
+ select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
select HAVE_FUNCTION_ARG_ACCESS_API