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    SubjectRe: [PATCH -tip] perf_counter/x86: Correct some event and umask values for Intel processors
    On Wed, Jun 10, 2009 at 12:42:42PM +0200, Ingo Molnar wrote:
    >
    > * Yong Wang <yong.y.wang@linux.intel.com> wrote:
    >
    > > On Tue, Jun 09, 2009 at 04:16:21PM +0200, Ingo Molnar wrote:
    > > >
    > > > * Yong Wang <yong.y.wang@linux.intel.com> wrote:
    > > >
    > > > > Correct some event and UMASK values according to Intel SDM.
    > > >
    > > > Very nice, thanks!
    > > >
    > > > were you able to test the Atom ones by any chance?
    > > >
    > >
    > > You bet I was as I'm working on Moblin ;-) [...]
    >
    > Heh :-)
    >
    > > [...] However, some work while some do not. I'll take a look at
    > > the problematic ones. With the previous event and umask values,
    > > the pmc does not count at all for some events, like l1d-write-ops.
    >
    > Interesting. I had a good look at the Atom details in the docs but
    > couldnt find anything suspicious. There's various umask level
    > extensions (sometimes cflags level ones) like whether to measure the
    > core or the thread, but the defaults (zero) seem to have OK
    > semantics for most of the events.
    >
    > Btw., when mapping out event tables there's one little trick i used
    > to 'scan' an event, using 'perf stat' and raw event numbers:
    >
    > for ((i=0;i<256;i++)); do \
    > perf stat -e $(printf "r%02x%02x\n" $i 0xc0) true 2>&1 | \
    > grep -w raw | grep -vw 0; \
    > done
    >
    > This scans all 256 umask values for the main event code of 0xc0, and
    > displays the umask values where the counter show some activity.
    >
    > ( if it's some rare event then you might want to run something else
    > that excercises that event, not /bin/true. )
    >

    Just took a look at the problematics ones and found that the fixed
    function PMCs do not work on current Atom processors. I tested on 3 Atom
    netbooks and the results are the same. Just sent a quirk patch for that.

    -Yong


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