powerpc/64: context tracking remove _TIF_NOHZ

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Add context tracking to the system call handler explicitly, and remove
_TIF_NOHZ.

This improves system call performance when nohz_full is enabled. On a
POWER9, gettid scv system call cost on a nohz_full CPU improves from
1129 cycles to 1004 cycles and on a housekeeping CPU from 550 cycles
to 430 cycles.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-31-npiggin@gmail.com

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Nicholas Piggin 2021-01-30 23:08:40 +10:00 • committed by Michael Ellerman

parent e6f8a6c86c

commit 2a06bf3e95

5 changed files with 47 additions and 38 deletions

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1

arch/powerpc/Kconfig

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4

arch/powerpc/include/asm/thread_info.h

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4

arch/powerpc/kernel/ptrace/ptrace.c

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4

arch/powerpc/kernel/signal.c

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72

arch/powerpc/kernel/syscall_64.c

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