[lkml]   [2004]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [patch] Latency Tracer, voluntary-preempt-2.6.8-rc4-O6

    * Andi Kleen <> wrote:

    > > > > yeah - kallsyms_lookup does a linear search over thousands of symbols.
    > > > > Especially since /proc/latency_trace uses it too it would be worthwile
    > > > > to implement some sort of binary searching.
    > > >
    > > > Or just stick some cond_sched()s in there. It was designed to be slow,
    > > > but there are no locking issues.
    > >
    > > the speedup would be important: even on a 2GHz box reading 10,000 trace
    > > entries takes a couple of seconds.
    > That's because you're abusing it - it was never designed to process
    > that much data.

    i'm not abusing it. Linear searching of 20 thousand symbols is a gross
    first-approximation algorithm no matter what. Yes, most users of the
    symbols dont care about performance. And i'm not complaining at all, i'm
    just pointing out the reason why e.g. printing a simple stack backtrace
    can take milliseconds.

    > With binary search you would need to backward search to find the stem
    > for the stem compression. It's probably doable, but would be a bit
    > ugly I guess.

    yeah. Maybe someone will find the time to improve the algorithm. But
    it's not a highprio thing.

    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: 2005-03-22 14:05    [W:0.031 / U:107.488 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site