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| author | Hou Tao <houtao1@huawei.com> | 2017-03-01 09:02:33 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-05-31 09:25:21 -0600 |
| commit | 5be6b75610cefd1e21b98a218211922c2feb6e08 (patch) | |
| tree | 6a1f5b0d5d66f5d8cec548d8ea5dcfa6b2ad8858 /block | |
| parent | e4dc2b32df5573b077f6723e01cf761d236d5113 (diff) | |
| download | linux-5be6b75610cefd1e21b98a218211922c2feb6e08.tar.bz2 | |
cfq-iosched: fix the delay of cfq_group's vdisktime under iops mode
When adding a cfq_group into the cfq service tree, we use CFQ_IDLE_DELAY
as the delay of cfq_group's vdisktime if there have been other cfq_groups
already.
When cfq is under iops mode, commit 9a7f38c42c2b ("cfq-iosched: Convert
from jiffies to nanoseconds") could result in a large iops delay and
lead to an abnormal io schedule delay for the added cfq_group. To fix
it, we just need to revert to the old CFQ_IDLE_DELAY value: HZ / 5
when iops mode is enabled.
Despite having the same value, the delay of a cfq_queue in idle class
and the delay of cfq_group are different things, so I define two new
macros for the delay of a cfq_group under time-slice mode and iops mode.
Fixes: 9a7f38c42c2b ("cfq-iosched: Convert from jiffies to nanoseconds")
Cc: <stable@vger.kernel.org> # 4.8+
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/cfq-iosched.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index da69b079725f..b7e9c7feeab2 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -38,9 +38,13 @@ static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */ static const int cfq_hist_divisor = 4; /* - * offset from end of service tree + * offset from end of queue service tree for idle class */ #define CFQ_IDLE_DELAY (NSEC_PER_SEC / 5) +/* offset from end of group service tree under time slice mode */ +#define CFQ_SLICE_MODE_GROUP_DELAY (NSEC_PER_SEC / 5) +/* offset from end of group service under IOPS mode */ +#define CFQ_IOPS_MODE_GROUP_DELAY (HZ / 5) /* * below this threshold, we consider thinktime immediate @@ -1362,6 +1366,14 @@ cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) cfqg->vfraction = max_t(unsigned, vfr, 1); } +static inline u64 cfq_get_cfqg_vdisktime_delay(struct cfq_data *cfqd) +{ + if (!iops_mode(cfqd)) + return CFQ_SLICE_MODE_GROUP_DELAY; + else + return CFQ_IOPS_MODE_GROUP_DELAY; +} + static void cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) { @@ -1381,7 +1393,8 @@ cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) n = rb_last(&st->rb); if (n) { __cfqg = rb_entry_cfqg(n); - cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; + cfqg->vdisktime = __cfqg->vdisktime + + cfq_get_cfqg_vdisktime_delay(cfqd); } else cfqg->vdisktime = st->min_vdisktime; cfq_group_service_tree_add(st, cfqg); |