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| author |   Tejun Heo <tj@kernel.org> | 2020-04-13 12:27:56 -0400 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2020-04-30 15:54:45 -0600 |
| commit | cd006509b0a93cb7ee9d9fd50ae274098997a460 (patch) | |
| tree | 1d3ab04a30ff6ac0f133195d9612702e5d77a881 /block/Kconfig | |
| parent | blk-iocost: switch to fixed non-auto-decaying use_delay (diff) | |
| download | wireguard-linux-cd006509b0a93cb7ee9d9fd50ae274098997a460.tar.xz wireguard-linux-cd006509b0a93cb7ee9d9fd50ae274098997a460.zip | |
blk-iocost: account for IO size when testing latencies
On each IO completion, iocost decides whether the IO met or missed its latency
target. Currently, the targets are fixed numbers per IO type. While this can be
good enough for loose latency targets way higher than typical completion
latencies, the effect of IO size makes it difficult to tighten the latency
target - a target adequate for 4k IOs might be too tight for 512k IOs and
vice-versa.
iocost already has all the necessary information to account for different IO
sizes when testing whether the latency target is met as iocost can calculate the
size vtime cost of a given IO. This patch updates the completion path to
calculate the size vtime cost of the IO, deduct the nsec equivalent from the
observed latency and use the adjusted value to decide whether the target is met.
This makes latency targets independent from IO size and enables determining
adequate latency targets with fixed size fio runs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andy Newell <newella@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/Kconfig')
| -rw-r--r-- | block/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/block/Kconfig b/block/Kconfig index 3bc76bb113a0..41cb34b0fcd1 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -146,6 +146,7 @@ config BLK_CGROUP_IOLATENCY config BLK_CGROUP_IOCOST bool "Enable support for cost model based cgroup IO controller" depends on BLK_CGROUP=y + select BLK_RQ_IO_DATA_LEN select BLK_RQ_ALLOC_TIME ---help--- Enabling this option enables the .weight interface for cost |