Re: command piped into bzip not using all available CPU

From: Jon Noack (noackjr_at_alumni.rice.edu)
Date: 04/17/04

  • Next message: Uwe Doering: "Re: How does disk caching work?" 
    Date: Fri, 16 Apr 2004 18:17:50 -0500
To: Aaron Seelye <aseelye-lists@eltopia.com>

    On 4/16/2004 5:48 PM, Aaron Seelye wrote:
    > I would venture a guess that bzip is not multi threaded and therefore
    > isn't spreading the load around.

    I think you may be right. I tested this on my dual Pentium III 933
    running 5.2.1-RELEASE-p5. bzip2 behaves like this while gzip behaves as
    expected. I know top sucks for measuring performance, but it should be
    accurate enough for the big picture.

    Here's the simple test with bzip2 (the rand() is to give perl "work"):
    perl -e 'do{print rand();}while 1' | bzip2 > /dev/null
    **********************************************************************
    last pid: 83786; load averages: 0.53, 0.31, 0.19 up 4+03:06:50
    17:54:52
    92 processes: 2 running, 90 sleeping
    CPU states: 52.0% user, 0.0% nice, 11.1% system, 0.4% interrupt, 36.5%
    idle
    Mem: 222M Active, 154M Inact, 99M Wired, 22M Cache, 60M Buf, 2140K Free
    Swap: 1024M Total, 176K Used, 1024M Free

       PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU CPU COMMAND
    83784 noackjr 106 0 8804K 7280K CPU0 0 0:22 60.19% 49.76% bzip2
    83783 noackjr -8 0 2756K 1908K pipdwt 0 0:14 38.87% 32.13% perl
    **********************************************************************

    This time with gzip (with -9 to make gzip work harder):
    perl -e 'do{print rand();}while 1' | gzip -9 > /dev/null
    **********************************************************************
    last pid: 83865; load averages: 1.11, 0.41, 0.28 up 4+03:18:11
    18:06:13
    91 processes: 4 running, 87 sleeping
    CPU states: 90.7% user, 0.0% nice, 1.6% system, 0.0% interrupt, 7.7%
    idle
    Mem: 215M Active, 155M Inact, 99M Wired, 19M Cache, 60M Buf, 10M Free
    Swap: 1024M Total, 176K Used, 1024M Free

       PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU CPU COMMAND
    83864 noackjr 117 0 2756K 1908K CPU0 0 0:32 88.37% 73.05% perl
    83865 noackjr 116 0 1696K 960K RUN 0 0:30 84.65% 69.97% gzip
    **********************************************************************

    On a moderately-related note, -CURRENT recently got some pipe updates
    (up to 75% bandwidth increase on i386):
    http://lists.freebsd.org/pipermail/cvs-src/2004-March/021197.html

    Jon Noack

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