Re: user:sys time ratio

From: Colin Percival (colin.percival_at_wadham.ox.ac.uk)
Date: 11/30/03

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    Date: Sun, 30 Nov 2003 19:54:12 +0000
To: freebsd-current@freebsd.org

       Robert Watson suggested that I compare performance from UP and SMP kernels:

    # /usr/bin/time -hl sh -c 'make -s buildworld 2>&1' > /dev/null
                       Real User Sys
       UP kernel 38m33.29s 27m10.09s 10m59.15s
          (retest) 38m33.18s 27m04.40s 11m05.73s
       SMP w/o HTT 41m01.54s 27m10.27s 13m29.82s
          (retest) 39m47.50s 27m08.05s 12m12.20s
       SMP w/HTT 42m17.16s 28m12.82s 14m04.93s
          (retest) 44m09.61s 28m15.31s 15m44.86s

       That enabling HTT degrades performance is not surprising, since I'm not
    passing the -j option to make; but a 5% performance delta between UP and
    SMP kernels is rather surprising (to me, at least), and the fact that the
    system time varies so much on the SMP kernel also seems peculiar.
       Is this normal?

    Colin Percival

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