user:sys time ratio

Colin Percival colin.percival at
Sun Nov 30 06:21:02 PST 2003

   I've got a system running 5.2-BETA from 27/11/03, with the malloc_abort, 
malloc_junk, DEBUG=-g, DDB, INVARIANT*, and WITNESS* debugging options 
changed (as was done in 5.1-RELEASE).
   When running `make buildworld`, I see large amounts of sys time; eg, 27 
minutes user & 14 minutes sys for building 5.2, or 14 minutes user & 10 
minutes sys for building 4.9.  I expected the ratio of user:sys to be much 
larger than this, and mailing list traffic indicates that a 4:1 ratio is 
typical.  (FWIW, prior to changing the debugging options, the user:sys time 
ratio was around 1:1.)
   Can anyone suggest why the kernel seems to be behaving so sluggishly?

   The system hardware is P4 2.8Ghz, 865G, 2GB DDR, IDE drives; there is 
very little disk activity, so I'm sure that isn't the issue; and disabling 
HTT results in about a 2% improvement in both user and sys times.

Colin Percival

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