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    SubjectRe: [patch 0/7] Add TRIM support for raid linear/0/1/10
    From
    2012/3/15 Holger Kiehl <Holger.Kiehl@dwd.de>:
    > On Wed, 14 Mar 2012, Shaohua Li wrote:
    >
    >> Maybe the discard runs slow with small size request in the disk.
    >> please drop patch "blk: add plug for blkdev_issue_discard" and try again.
    >> Since
    >> we can't do merge, the plug just introduces latency.
    >>
    > Tried again without the patch applied, but there is only a very small
    > performance increase (520->600 agains 4000 fps without discard).
    >
    > The benchmark creates lots of small files (2 KiB) and deletes them again.
    >
    >
    >> if it doesn't help, please capture a blktrace when you do the benchmark
    >> and
    >> send it to me.
    >>
    > Ok, I will do this tomorrow. Need some sleep :-)
    >
    > Thanks for your work on supporting discard in MD!
    I tried your benchmark, create 2000k 2k files and delete them and
    follows a sync.
    the discard runs pretty fast for both raid 0/1. So can't reproduce the
    issue. I'm using
    a fusionio card though. I'm afraid nothing I can do till get you blktrace.

    Thanks,
    Shaohua


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