blk-iocost: implement vtime loss compensation

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When an iocg accumulates too much vtime or gets deactivated, we throw away
some vtime, which lowers the overall device utilization. As the exact amount
which is being thrown away is known, we can compensate by accelerating the
vrate accordingly so that the extra vtime generated in the current period
matches what got lost.

This significantly improves work conservation when involving high weight
cgroups with intermittent and bursty IO patterns.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Tejun Heo 2020-09-01 14:52:54 -04:00 • committed by Jens Axboe

parent dda1315f18

commit ac33e91e2d

1 changed files with 90 additions and 42 deletions

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block/blk-iocost.c

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