sched: Bring the PF_IO_WORKER and PF_WQ_WORKER bits closer together

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The bits PF_IO_WORKER and PF_WQ_WORKER are tested together in
sched_submit_work() which is considered to be a hot path.
If the two bits cross the 8 or 16 bit boundary then most architecture
require multiple load instructions in order to create the constant
value. Also, such a value can not be encoded within the compare opcode.

By moving the bit definition within the same block, the compiler can
create/use one immediate value.

For some reason gcc-10 on ARM64 requires both bits to be next to each
other in order to issue "tst reg, val; bne label". Otherwise the result
is "mov reg1, val; tst reg, reg1; bne label".

Move PF_VCPU out of the way so that PF_IO_WORKER can be next to
PF_WQ_WORKER.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200819195505.y3fxk72sotnrkczi@linutronix.de

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Sebastian Andrzej Siewior 2020-08-19 21:55:05 +02:00 • committed by Peter Zijlstra

parent 1724b95b92

commit 01ccf59236

1 changed files with 2 additions and 2 deletions

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include/linux/sched.h

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