lkml.org 
[lkml]   [2000]   [Aug]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [patch] lowlatency patch for 2.4, lowlatency-2.4.0-test6-B5
    yodaiken@fsmlabs.com wrote:
    >
    > On Fri, Aug 04, 2000 at 03:43:15PM +0200, Ingo Molnar wrote:
    > > *no*. There are places in the kernel that do work for millisecs while
    > > holding a spinlock. This causes millisec latencies even if we had a
    >
    > The interesting question here is "why"? The only example ever discussed
    > here was copying data on big reads/writes and this seems like a classic
    > case of where the algorithm needs to be fixed -- if you have a millisecond
    > copy then you almost certainly would benefit from kiobufs or something smart.

    The only expensive one which of which I'm aware is the lock in
    zap_page_range(): "This is a long-lived spinlock.".

    My approach here was to bust zap_page_range() up into 512-page chunks with
    one reschedule per chunk. Ingo's patch does this on a per-page basis: tests
    need_resched and then, if required, drops the lock and reschedules.

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:58    [W:3.116 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site