Messages in this thread | | | Date | Sun, 25 Feb 2007 18:46:52 -0500 | From | Rik van Riel <> | Subject | Re: SMP performance degradation with sysbench |
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Lorenzo Allegrucci wrote: > Hi lkml, > > according to the test below (sysbench) Linux seems to have scalability > problems beyond 8 client threads: > http://jeffr-tech.livejournal.com/6268.html#cutid1 > http://jeffr-tech.livejournal.com/5705.html > Hardware is an 8-core amd64 system and jeffr seems willing to try more > Linux versions on that machine. > Anyway, is there anyone who can reproduce this?
I have reproduced it on a quad core test system.
With 4 threads (on 4 cores) I get a high throughput, with approximately 58% user time and 42% system time.
With 8 threads (on 4 cores) I get way lower throughput, with 37% user time, 29% system time 35% idle time!
The maximum time taken per query also increases from 0.0096s to 0.5273s. Ouch!
I don't know if this is MySQL, glibc or Linux kernel, but something strange is going on...
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