[lkml]   [2006]   [Sep]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH 0/6] Per-processor private data areas for i386
    Pavel Machek wrote:
    > So we have 4% slowdown...

    Yes, that would be the worst-case slowdown in the hot-cache case.
    Rearranging the layout of the GDT would remove any theoretical
    cold-cache slowdown (I haven't measured if there's any impact in practice).

    > ...and 0.2% smaller kernel. I guess you should demonstrate speedup at
    > complex syscalls before wedecide it is worth it...

    That would be nice, but this patch series isn't really intended to be a
    performance improvement. That would be nice, but the main motivation is
    to make inline assembler patching for the paravirt work cleaner.

    Rusty and I have also been investigating how to use the %gs-based memory
    to implement all percpu data, rather than the few special cases this
    patch series currently covers, which will help further amortize the
    entry/exit cost.

    Rusty has also done more comprehensive benchmarks with his variant of
    this patch series, and found no statistically interesting performance
    difference. Which is pretty much what I would expect, since it doesn't
    increase cache-misses at all.

    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: 2006-09-27 22:31    [W:0.027 / U:1.392 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site