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    cfq-iosched: don't let idling interfere with plugging · b029195d
    Jens Axboe 提交于
    When CFQ is waiting for a new request from a process, currently it'll
    immediately restart queuing when it sees such a request. This doesn't
    work very well with streamed IO, since we then end up splitting IO
    that would otherwise have been merged nicely. For a simple dd test,
    this causes 10x as many requests to be issued as we should have.
    Normally this goes unnoticed due to the low overhead of requests
    at the device side, but some hardware is very sensitive to request
    sizes and there it can cause big slow downs.
    Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
    b029195d
cfq-iosched.c 58.5 KB