Re: [RFC PATCH] block: Fix bio merge induced high I/O latency

From: Ben Gamari
Date: Tue Jan 20 2009 - 15:22:24 EST


On Tue, Jan 20, 2009 at 2:37 AM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
> On Mon, Jan 19 2009, Mathieu Desnoyers wrote:
>> * Jens Axboe (jens.axboe@xxxxxxxxxx) wrote:
>> Yes, ideally I should re-run those directly on the disk partitions.
>
> At least for comparison.
>

I just completed my own set of benchmarks using the fio job file
Mathieu provided. This was on a 2.5 inch 7200 RPM SATA partition
formatted as ext3. As you can see, I tested all of the available
schedulers with both queuing enabled and disabled. I'll test the Jens'
patch soon. Would a blktrace of the fio run help? Let me know if
there's any other benchmarking or profiling that could be done.
Thanks,

- Ben


mint maxt
==========================================================
queue_depth=31:
anticipatory 35 msec 11036 msec
cfq 37 msec 3350 msec
deadline 36 msec 18144 msec
noop 39 msec 41512 msec

==========================================================
queue_depth=1:
anticipatory 45 msec 9561 msec
cfq 28 msec 3974 msec
deadline 47 msec 16802 msec
noop 35 msec 38173 msec
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