> On Thu, 29 May 2008 00:02:50 -0700 (PDT)
>
youquan_song@linux.intel.com wrote:
>
> > cpufreq_ondemand governor call queue_delayed_work_on with entry
> > parameter "cpu" every sample rate(every logical cpu during
> > 20ms).check the value of "cpu","cpu>=0" condition meeting rate is
> > over than 90%.
> >
> > This patch remove the unlikely macros to benefit kernel schedule and
> > reader comprehension.
> >
> > Signed-off-by: Youquan Song <youquan.song@intel.com>
> > ---
> > workqueue.c | 2++++++
> > 1 file changed, 1 insertions(+), 1 deletions(-)
> >
> > --- linux-2.6/kernel/workqueue.c 2008-05-13
> > 10:10:11.000000000 -0400 +++
> > linux-2.6-new/kernel/workqueue.c 2008-05-29
> > 09:46:16.000000000 -0400 @@ -230,7 +230,7 @@ timer->data =
> > (unsigned long)dwork; timer->function = delayed_work_timer_fn;
> >
> > - if (unlikely(cpu >= 0))
> > + if (cpu >= 0)
> > add_timer_on(timer, cpu);
> > else
> > add_timer(timer);
> >
>
> This is very much dependent on what workload the machine is running.
>
> There are 189 queue_delayed_work() callsites and they all want the
> unlikely() to be there.
>
> There are six queue_delayed_work_on() callsites and they don't want
> the unlikely().
>
> Don't know what to do here. Fortunately it doesn't matter much ;)
>
> -mm has profile-likely-unlikely-macros.patch which can be used to
> instrument these things (that feature seems to get broken regularly
> though).
>
> But the instrumentation should be performed across a broad range of
> workloads.
