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    SubjectRe: CFS scheduler OLTP perforamnce
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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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