Messages in this thread | | | Date | Tue, 16 Oct 2012 09:32:11 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [RESEND PATCH 2/2] perf, cpu hotplug: Use cached value of smp_processor_id() |
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On Tue, Oct 16, 2012 at 01:28:17PM +0530, Srivatsa S. Bhat wrote: > The perf_cpu_notifier() macro invokes smp_processor_id() multiple > times. Optimize it by using a local variable. > > Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> --- > > include/linux/perf_event.h | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 0647805..6bfb2faa 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -803,15 +803,16 @@ static inline void perf_event_task_tick(void) { } > do { \ > static struct notifier_block fn##_nb __cpuinitdata = \ > { .notifier_call = fn, .priority = CPU_PRI_PERF }; \ > + unsigned long cpu = smp_processor_id(); \ > unsigned long flags; \ > fn(&fn##_nb, (unsigned long)CPU_UP_PREPARE, \ > - (void *)(unsigned long)smp_processor_id()); \ > + (void *)(unsigned long)cpu); \ > local_irq_save(flags); \ > fn(&fn##_nb, (unsigned long)CPU_STARTING, \ > - (void *)(unsigned long)smp_processor_id()); \ > + (void *)(unsigned long)cpu); \ > local_irq_restore(flags); \ > fn(&fn##_nb, (unsigned long)CPU_ONLINE, \ > - (void *)(unsigned long)smp_processor_id()); \ > + (void *)(unsigned long)cpu); \ > register_cpu_notifier(&fn##_nb); \ > } while (0) > >
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