Messages in this thread | | | Subject | Re: CFS scheduler OLTP perforamnce | From | Peter Zijlstra <> | Date | Fri, 12 Dec 2008 13:12:13 +0100 |
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On Thu, 2008-12-11 at 16:25 -0700, Ma, Chinang wrote: > We are evaluating the CFS OLTP performance with 2.6.28-c7 kernel. In > this workload once a database foreground process commit a transaction > it will signal the log writer process to write to the log file. > Foreground processes will wait until log writer finish writing and > wake them up. With hundreds of foreground process running in the > system, it is important that the log writer get to run as soon as data > is available. > > Here are the experiments we have done with 2.6.28-rc7. > 1. Increase log writer priority "renice -20 <log writer pid>" while > keeping all other processes running in default CFS priority. We get a > baseline performance with log latency (scheduling + i/o) at 7 ms.
Is this better or the same than nice-0 ?
> 2. To reduce log latency, we set log writer to SCHED_RR with higher > priority. We tried "chrt -p 49 <log writer pid>" and got 0.7% boost > in performance with log latency reduced to 6.4 ms. > > It seems that in this case renice to higher priority with CFS did not > reduce scheduling latency as well as SCHED_RR.
Is there a question in this email?
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