[lkml]   [2012]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [tip:perf/core] perf ui annotate browser: Allow toggling addr offset view
    On Fri, Apr 13, 2012 at 11:25 AM, Linus Torvalds
    <> wrote:
    > <kmem_cache_free>:
    >    1.91 :          push   %rbp

    Oh, btw, talking about kmem_cache_free: that one uses altinstructions,
    and so perf report shows the hottest instruction wrong (and I'm not
    talking about "ugly"):

    12.38 : ffffffff810d7ee5: lea (%r8),%rsi
    0.71 : ffffffff810d7ee8: callq ffffffff812d3df0

    that "lea" really isn't very expensive. In reality, it's not
    "lea+call", it's a "lock ; cmpxchg16b + setz" instruction. But "perf"
    doesn't know about alternative instructions, and if somebody were to
    try to teach it, that would be lovely.

    Happily, x86-64 doesn't have quite as many of them as x86-32 does. But
    they are there, sometimes in interesting functions.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2012-04-13 20:33    [W:0.019 / U:221.560 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site