lkml.org 
[lkml]   [2010]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH] perf_events: AMD event scheduling (v3)
    From
    On Wed, Feb 10, 2010 at 2:28 PM, Peter Zijlstra <peterz@infradead.org> wrote:
    > On Wed, 2010-02-10 at 14:17 +0100, Peter Zijlstra wrote:
    >> On Wed, 2010-02-10 at 14:04 +0100, Stephane Eranian wrote:
    >>
    >> > > @@ -2268,7 +2268,7 @@ static inline int amd_is_nb_event(struct
    >> > >        u64 val = hwc->config & K7_EVNTSEL_EVENT_MASK;
    >> > >        /* event code : bits [35-32] | [7-0] */
    >> > >        val = (val >> 24) | (val & 0xff);
    >> > > -       return val >= 0x0e0;
    >> > > +       return val >= 0xe00;
    >> > >  }
    >> > >
    >> > I don't understand the change from 0xe0 to 0xe00.
    >> > That's not the same thing at all.
    >> > Event select is bits 0-7 + 32-35.
    >>
    >> OK that appears to be my bad, because you extended K7_EVNTSEL_EVENT_MASK
    >> with bit 35 I thought NB events all had bit 35 set.
    >>
    >> But looking at the AMD docs it does indeed appear to start at 0xe0, and
    >> there are no events with bit 35 set, only a few with bit 32.
    >>
    >> I'll switch it back to 0xe0.
    >
    > Fwiw, for the purpose of that function you might as well write:
    >
    > static inline int amd_is_nb_event(struct hw_perf_event *hwc)
    > {
    >        return (hwc->config & K7_EVNTSEL_EVENT_MASK) > 0xe0;
    > }
    >
    > No need to move bits around higher than the value you compare against.
    >
    I think given the existing event codes, that would be fine too.
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2010-02-10 15:01    [W:0.045 / U:91.864 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site