x86/smp: Enhance native_send_call_func_ipi()

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Nadav noticed that the cpumask allocations in native_send_call_func_ipi()
are noticeable in microbenchmarks.

Use the new cpumask_or_equal() function to simplify the decision whether
the supplied target CPU mask is either equal to cpu_online_mask or equal to
cpu_online_mask except for the CPU on which the function is invoked.

cpumask_or_equal() or's the target mask and the cpumask of the current CPU
together and compares it to cpu_online_mask.

If the result is false, use the mask based IPI function, otherwise check
whether the current CPU is set in the target mask and invoke either the
send_IPI_all() or the send_IPI_allbutselt() APIC callback.

Make the shorthand decision also depend on the static key which enables
shorthand mode. That allows to remove the extra cpumask comparison with
cpu_callout_mask.

Reported-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105220.768238809@linutronix.de

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This commit is contained in:

Thomas Gleixner 2019-07-22 20:47:26 +02:00

parent d0a7166bc7

commit 832df3d47b

1 changed files with 11 additions and 13 deletions

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arch/x86/kernel/apic/ipi.c

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