lkml.org 
[lkml]   [2007]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRE: [patch 0/3] no MAX_ARG_PAGES -v2
    Date
    From
    > This patch-set aims at removing the current limit on argv+env space aka.
    > MAX_ARG_PAGES.

    Running with this patch shows that /bin/bash has some unpleasant
    O(n^2) performance issues with long argument lists. I made a
    1Mbyte file full of pathnames, then timed the execution of:

    $ /bin/echo `cat megabyte` | wc
    $ /bin/echo `cat megabyte megabyte` | wc
    etc. ...

    System time was pretty much linear as the arglist grew
    (and only got up to 0.144 seconds at 5Mbytes).

    But user time ~= real time (in seconds) looks like:

    1 5.318
    2 18.871
    3 40.620
    4 70.819
    5 108.911

    Above 5Mbytes, I started seeing problems. The line/word/char
    counts from "wc" started being "0 0 0". Not sure if this is
    a problem in "wc" dealing with a single line >5MBytes, or some
    other problem (possibly I was exceeding the per-process stack
    limit which is only 8MB on that machine).

    -Tony
    -
    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: 2007-06-14 01:39    [W:0.022 / U:0.600 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site