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authorTejun Heo <tj@kernel.org>2019-09-25 16:03:35 -0700
committerJens Axboe <axboe@kernel.dk>2019-09-26 01:12:01 -0600
commit7afcccafa59fb63b58f863a6c5e603a34625955b (patch)
tree90411b8d597331af31f552839cb11fb81f2cd7e7 /block
parent7cd806a9a953f234b9865c30028f47fd738ce375 (diff)
iocost: bump up default latency targets for hard disks
The default hard disk param sets latency targets at 50ms. As the default target percentiles are zero, these don't directly regulate vrate; however, they're still used to calculate the period length - 100ms in this case. This is excessively low. A SATA drive with QD32 saturated with random IOs can easily reach avg completion latency of several hundred msecs. A period duration which is substantially lower than avg completion latency can lead to wildly fluctuating vrate. Let's bump up the default latency targets to 250ms so that the period duration is sufficiently long. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-iocost.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 10160de62e3b..2a3db80c1dce 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -529,8 +529,8 @@ struct iocg_wake_ctx {
static const struct ioc_params autop[] = {
[AUTOP_HDD] = {
.qos = {
- [QOS_RLAT] = 50000, /* 50ms */
- [QOS_WLAT] = 50000,
+ [QOS_RLAT] = 250000, /* 250ms */
+ [QOS_WLAT] = 250000,
[QOS_MIN] = VRATE_MIN_PPM,
[QOS_MAX] = VRATE_MAX_PPM,
},

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