sched: Cache task_struct::flags in sched_submit_work()

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sched_submit_work() is considered to be a hot path. The preempt_disable()
instruction is a compiler barrier and forces the compiler to load
task_struct::flags for the second comparison.
By using a local variable, the compiler can load the value once and keep it in
a register for the second comparison.

Verified on x86-64 with gcc-10.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200819200025.lqvmyefqnbok5i4f@linutronix.de

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Sebastian Andrzej Siewior 2020-08-19 22:00:25 +02:00 • committed by Peter Zijlstra

parent 01ccf59236

commit c1cecf884a

1 changed files with 5 additions and 2 deletions

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kernel/sched/core.c

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