Re: user:sys time ratio

From: Colin Percival <colin.percival_at_wadham.ox.ac.uk>
Date: Sun, 30 Nov 2003 19:54:12 +0000
   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
Received on Sun Nov 30 2003 - 10:54:18 UTC

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