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block, bfq: use half slice_idle as a threshold to check short ttime
authorPaolo Valente <paolo.valente@linaro.org>
Fri, 22 Jan 2021 18:19:43 +0000 (19:19 +0100)
committerJens Axboe <axboe@kernel.dk>
Mon, 25 Jan 2021 01:18:24 +0000 (18:18 -0700)
commitb5f74ecacc3139ef873e69acc3aba28083ecc416
tree8f370be89b909cd104670a7f19c8a805ee324ef3
parenta33df75c6328bf40078b35f2040d8e54d574c357
block, bfq: use half slice_idle as a threshold to check short ttime

The value of the I/O plugging (idling) timeout is used also as the
think-time threshold to decide whether a process has a short think
time.  In this respect, a good value of this timeout for rotational
drives is un the order of several ms. Yet, this is often too long a
time interval to be effective as a think-time threshold. This commit
mitigates this problem (by a lot, according to tests), by halving the
threshold.

Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/bfq-iosched.c