[lkml]   [2004]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: 2.4.23aa2 (bugfixes and important VM improvements for the high end)
    Andrea Arcangeli wrote:
    > > Can you use a read-write lock, so that userspace copies only need to
    > > take the lock for reading? That doesn't eliminate cacheline bouncing
    > > but does eliminate the serialisation.
    > normally the bouncing would be the only overhead, but here I also think
    > the serialization is a significant factor of the contention because the
    > critical section is taking lots of time. So I would expect some
    > improvement by using a read/write lock.

    For something as significant as user<->kernel data transfers, it might
    be worth eliminating the bouncing as well - by using per-CPU * per-mm

    User<->kernel data transfers would take the appropriate per-CPU lock
    for the current mm, and not take page_table_lock. Everything that
    normally takes page_table_lock would, and also take all of the per-CPU locks.

    That does require a set of per-CPU spinlocks to be allocated whenever
    a new mm is allocated (although the sets could be cached so it needn't
    be slow).

    -- Jamie
    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 14:01    [W:0.024 / U:10.248 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site