powerpc/64s/idle: avoid sync for KVM state when waking from idle

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When waking from a CPU idle instruction (e.g., nap or stop), the sync
for ordering the KVM secondary thread state can be avoided if there
wakeup is coming from a kernel context rather than KVM context.

This improves performance for ping-pong benchmark with the stop0 idle
state by 0.46% for 2 threads in the same core, and 1.02% for different
cores.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Nicholas Piggin 2017-11-18 00:08:06 +10:00 • committed by Michael Ellerman

parent 3d4fbffdd7

commit 8c1c7fb0b5

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arch/powerpc/kernel/idle_book3s.S

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