2 x quad-core system is slower that 2 x dual core on FreeBSD

Kris Kennaway kris at FreeBSD.org
Wed Nov 21 03:15:13 PST 2007

Alexey Popov wrote:

> Also could you explain what to look for in the lock profiling results? 
> Does large "wait_total" values indicate problem or other columns???

All of the columns (well, maybe except for the "lock name" ;-) can 
indicate potential problems of various kinds, so you have to look at 
them all to identify possible abnormalities.

For example, if you are acquiring a mutex many times you might look for 
ways to reduce the frequency of acquisitions.  If it is being held for 
long periods of time this can increase contention for other consumers. 
If there is high lock contention then processes will block waiting for 
it.  If processes are spending a lot of time waiting for the lock then 
they are not getting work done.


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