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SubjectRe: [PATCH 0/6 v3] cpuidle: Handle TIF_NR_POLLING on behalf of polling idle states
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Hello Frederic,

On 1/2/2025 8:31 PM, Frederic Weisbecker wrote:
> The TIF_NR_POLLING handling against TIF_NEED_RESCHED polling/monitoring
> idle states (mwait and also software polling) is a bit messy, with quite
> some wasted cycles spent on useless atomic operations. This tries to
> consolidate this state handling from the cpuidle core.

I tested this series on my 3rd Generation EPYC System with ipistorm and
I've not observed any regressions in IPI throughput to idle CPUs in
TIF_POLLING mode. Additionally tested few microbenchmarks and there were
no surprises there either. Feel free to add:

Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>

--
Thanks and Regards,
Prateek

>
> Changes since v2:
>
> _ Handle buggy mwait implementations (thanks Rafael)
>
> Frederic Weisbecker (4):
> cpuidle: Remove unnecessary current_clr_polling_and_test() from
> haltpoll
> x86/cpuidle: Move buggy mwait implementations away from
> CPUIDLE_FLAG_MWAIT
> cpuidle: Remove call_cpuidle_s2idle()
> cpuidle: Handle TIF_NR_POLLING on behalf of software polling idle
> states
>
> Peter Zijlstra (2):
> cpuidle: Introduce CPUIDLE_FLAG_MWAIT
> cpuidle: Handle TIF_NR_POLLING on behalf of CPUIDLE_FLAG_MWAIT states
>
> arch/arm/include/asm/cpuidle.h | 2 ++
> arch/arm64/include/asm/cpuidle.h | 3 ++
> arch/powerpc/include/asm/cpuidle.h | 4 +++
> arch/riscv/include/asm/cpuidle.h | 2 ++
> arch/x86/include/asm/cpuidle.h | 12 +++++++
> arch/x86/include/asm/mwait.h | 27 +++++++--------
> drivers/acpi/processor_idle.c | 5 +++
> drivers/cpuidle/cpuidle-haltpoll.c | 3 --
> drivers/cpuidle/cpuidle-powernv.c | 10 ------
> drivers/cpuidle/cpuidle-pseries.c | 11 -------
> drivers/cpuidle/cpuidle.c | 22 ++++++++++++-
> drivers/cpuidle/poll_state.c | 30 +++++++----------
> drivers/idle/intel_idle.c | 8 +++++
> include/asm-generic/Kbuild | 1 +
> include/asm-generic/cpuidle.h | 10 ++++++
> include/linux/cpuidle.h | 1 +
> include/linux/sched/idle.h | 7 +++-
> kernel/sched/idle.c | 53 +++++++++---------------------
> 18 files changed, 114 insertions(+), 97 deletions(-)
> create mode 100644 arch/x86/include/asm/cpuidle.h
> create mode 100644 include/asm-generic/cpuidle.h
>


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