Messages in this thread | | | From | "Ma, Chinang" <> | Date | Fri, 12 Dec 2008 10:25:47 -0700 | Subject | RE: CFS scheduler OLTP perforamnce |
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>-----Original Message----- >From: Peter Zijlstra [mailto:peterz@infradead.org] >Sent: Friday, December 12, 2008 4:12 AM >To: Ma, Chinang >Cc: Ingo Molnar; linux-kernel@vger.kernel.org; Wilcox, Matthew R; Van De >Ven, Arjan; Styner, Douglas W; Chilukuri, Harita; Wang, Peter Xihong; >Nueckel, Hubert >Subject: Re: CFS scheduler OLTP perforamnce > >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? >
Can renice performance as well as SCHED_RR?
-Chinang
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