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Subject: Re: [PATCH] block: BFQ default for single queue devices
From: Bart Van Assche <bvanassche@acm.org>
To: Paolo Valente <paolo.valente@linaro.org>, Jens Axboe <axboe@kernel.dk>
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Date: Wed, 03 Oct 2018 08:54:51 -0700
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On Wed, 2018-10-03 at 08:29 +-0200, Paolo Valente wrote:
+AD4 +AFs-1+AF0 https://lkml.org/lkml/2017/2/21/791
+AD4 +AFs-2+AF0 http://algo.ing.unimo.it/people/paolo/disk+AF8-sched/results.php
+AD4 +AFs-3+AF0 https://lwn.net/Articles/763603/

>>From +AFs-2+AF0: +ACI-BFQ loses about 18+ACU with only random readers, because the number
of IOPS becomes so high that the execution time and parallel efficiency of
the schedulers becomes relevant.+ACI Since the number of I/O patterns for which
results are available on +AFs-2+AF0 is limited and since the number of devices for
which test results are available on +AFs-2+AF0 is limited (e.g. RAID is missing),
there might be other cases in which configuring BFQ as the default would
introduce a regression.

I agree with Jens that it's best to leave it to the Linux distributors to
select a default I/O scheduler.

Bart.