Messages in this thread | | | Subject | Re: bdflush/rpciod high CPU utilization, profile does not make sense | From | Trond Myklebust <> | Date | Sun, 24 Apr 2005 23:09:58 -0400 |
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su den 24.04.2005 Klokka 09:15 (+0200) skreiv Jakob Oestergaard: > Performance on SMP NFS client: > File Block Num Seq Read Rand Read Seq Write Rand Write > Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%) > ------- ------ ------- --- ----------- ----------- ----------- ----------- > . 2000 4096 1 47.53 80.0% 5.013 2.79% 22.34 32.2% 6.510 14.9% > . 2000 4096 2 45.29 78.6% 8.068 5.44% 24.53 34.1% 7.042 14.9% > . 2000 4096 4 45.38 78.0% 11.02 7.95% 25.13 35.1% 7.525 18.0% > > Performance on UP NFS client: > File Block Num Seq Read Rand Read Seq Write Rand Write > Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%) > ------- ------ ------- --- ----------- ----------- ----------- ----------- > . 2000 4096 1 57.11 54.7% 69.60 24.9% 35.09 14.2% 6.656 19.1% > . 2000 4096 2 60.11 58.8% 70.99 30.8% 33.82 14.1% 7.283 25.1% > . 2000 4096 4 67.89 59.8% 42.10 19.1% 29.86 12.7% 7.850 26.4% > > So, by booting the NFS client in uniprocessor mode, I got a 50% write > performance boost, 20% read perforamance boost, and the tests use about > half the CPU time. > > Isn't this a little disturbing? :)
Actually, the most telling difference here is with the random read rates which shows up to 1000% difference. I seriously doubt that has much to do with lock contention (given that the sequential reads show 20% as you said).
Could you once again have a look at the retransmission rates (both UDP and TCP), comparing the SMP and UP cases?
Cheers, Trond -- Trond Myklebust <trond.myklebust@fys.uio.no>
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