Messages in this thread | | | From | Linus Torvalds <> | Date | Wed, 22 May 2019 12:54:13 -0700 | Subject | Re: [PATCH] locking/lock_events: Use this_cpu_add() when necessary |
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On Wed, May 22, 2019 at 8:40 AM Waiman Long <longman@redhat.com> wrote: > > +#if defined(CONFIG_PREEMPT) && \ > + (defined(CONFIG_DEBUG_PREEMPT) || !defined(CONFIG_X86)) > +#define lockevent_percpu_inc(x) this_cpu_inc(x) > +#define lockevent_percpu_add(x, v) this_cpu_add(x, v)
Why that CONFIG_X86 special case?
On x86, the regular non-underscore versionm is perfectly fine, and the underscore is no faster or simpler.
So just make it be
#if defined(CONFIG_PREEMPT) .. non-underscore versions.. #else .. underscore versions .. #endif
and realize that x86 simply doesn't _care_. On x86, it will be one single instruction regardless.
Non-x86 may prefer the underscore versions for the non-preempt case.
Linus
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