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blk-iocost: Move the usage ratio calculation to the correct place

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We only use the hweight based usage ratio to calculate the new
hweight_inuse of the iocg to decide if this iocg can donate some
surplus vtime.

Thus move the usage ratio calculation to the correct place to
avoid unnecessary calculation for some vtime shortage iocgs.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Baolin Wang 2020-11-26 16:16:13 +08:00 committed by Jens Axboe
parent 647c9f03b2
commit c09245f61c
1 changed files with 23 additions and 21 deletions
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44
block/blk-iocost.c
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@ -2168,8 +2168,8 @@ static void ioc_timer_fn(struct timer_list *timer)
/* calc usage and see whether some weights need to be moved around */
list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
u64 vdone, vtime, usage_us, usage_dur;
u32 usage, hw_active, hw_inuse;
u64 vdone, vtime, usage_us;
u32 hw_active, hw_inuse;
/*
* Collect unused and wind vtime closer to vnow to prevent
@ -2200,30 +2200,32 @@ static void ioc_timer_fn(struct timer_list *timer)
usage_us = iocg->usage_delta_us;
usage_us_sum += usage_us;
if (vdone != vtime) {
u64 inflight_us = DIV64_U64_ROUND_UP(
cost_to_abs_cost(vtime - vdone, hw_inuse),
ioc->vtime_base_rate);
usage_us = max(usage_us, inflight_us);
}
/* convert to hweight based usage ratio */
if (time_after64(iocg->activated_at, ioc->period_at))
usage_dur = max_t(u64, now.now - iocg->activated_at, 1);
else
usage_dur = max_t(u64, now.now - ioc->period_at, 1);
usage = clamp_t(u32,
DIV64_U64_ROUND_UP(usage_us * WEIGHT_ONE,
usage_dur),
1, WEIGHT_ONE);
/* see whether there's surplus vtime */
WARN_ON_ONCE(!list_empty(&iocg->surplus_list));
if (hw_inuse < hw_active ||
(!waitqueue_active(&iocg->waitq) &&
time_before64(vtime, now.vnow - ioc->margins.low))) {
u32 hwa, old_hwi, hwm, new_hwi;
u32 hwa, old_hwi, hwm, new_hwi, usage;
u64 usage_dur;
if (vdone != vtime) {
u64 inflight_us = DIV64_U64_ROUND_UP(
cost_to_abs_cost(vtime - vdone, hw_inuse),
ioc->vtime_base_rate);
usage_us = max(usage_us, inflight_us);
}
/* convert to hweight based usage ratio */
if (time_after64(iocg->activated_at, ioc->period_at))
usage_dur = max_t(u64, now.now - iocg->activated_at, 1);
else
usage_dur = max_t(u64, now.now - ioc->period_at, 1);
usage = clamp_t(u32,
DIV64_U64_ROUND_UP(usage_us * WEIGHT_ONE,
usage_dur),
1, WEIGHT_ONE);
/*
* Already donating or accumulated enough to start.