lkml.org 
[lkml]   [2002]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: 3x slower file reading oddity
    On Mon, 17 Jun 2002, Benjamin LaHaise wrote:

    > On Mon, Jun 17, 2002 at 01:03:15PM -0700, dean gaudet wrote:
    > > 3x slower with the two cats in parallel.
    >
    > cat uses an incredibly small buffer for file io (4KB on x86), so
    > running multiple cats in parallel will simply thrash your disk.
    > What you really want is to run the open()s in parallel and the
    > read()s sequentially (or in parallel with a large buffer to cut
    > down on the seek cost).

    using a 64KB buffer makes the xargs -P2 only twice as long as the -P1 ...
    so that's an improvement, but still something seems odd. (btw, many of
    the files are tiny anyhow -- a bunch of maildirs mixed in amongst the
    files.)

    i'll try playing around with threading the open()s.

    -dean

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

    \
     
     \ /
      Last update: 2005-03-22 13:26    [W:2.962 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site