linux-kernel - Re: [PATCH] perf/core: Enable the bp only if the .disable field is 0.

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Message-ID: <20171127092438.GA23704@krava>
Date:   Mon, 27 Nov 2017 10:25:37 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Milind Chabbi <chabbi.milind@...il.com>
Cc:     Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Paul Mackerras <paulus@...ba.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/core: Enable the bp only if the .disable field is 0.

On Sun, Nov 26, 2017 at 10:50:27PM -0800, Milind Chabbi wrote:
> On Sun, Nov 26, 2017 at 10:43 PM, Milind Chabbi <chabbi.milind@...il.com> wrote:
> > Signed-off-by: Milind Chabbi <chabbi.milind@...il.com>
> > ---
> >  kernel/events/core.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index 35747a58ffb4..1b8eae85e9de 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -2659,7 +2659,8 @@ static int perf_event_modify_breakpoint(struct perf_event *bp,
> >                 return err;
> >         }
> >
> > -       _perf_event_enable(bp);
> > +       if (!attr->disabled)
> > +               _perf_event_enable(bp);
> >         return 0;
> >  }
> >
> > --
> > 2.14.1
> >
> 
> Hi Jirka,
> Thanks for your changes for proper accounting of the bp.
> This additional change is needed so that we do not enable the bp if
> the user has not asked to enable it.
> I did the testing for ioctl and it continues to show the significant
> speedups that I had originally seen.

right, I'll merge this in and post

thanks,
jirka