2022-09-29 07:43:46

by Kemeng Shi

[permalink] [raw]
Subject: [PATCH 3/3] block: Replace struct rq_depth with unsigned int in struct iolatency_grp

We only need a max queue depth for every iolatency to limit the inflight io
number. Replace struct rq_depth with unsigned int to simplfy "struct
iolatency_grp" and save memory.

Signed-off-by: Kemeng Shi <[email protected]>
---
block/blk-iolatency.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 2666afd7abdb..55bc742d3b66 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -141,7 +141,7 @@ struct iolatency_grp {
struct latency_stat __percpu *stats;
struct latency_stat cur_stat;
struct blk_iolatency *blkiolat;
- struct rq_depth rq_depth;
+ unsigned int max_depth;
struct rq_wait rq_wait;
atomic64_t window_start;
atomic_t scale_cookie;
@@ -280,7 +280,7 @@ static void iolat_cleanup_cb(struct rq_wait *rqw, void *private_data)
static bool iolat_acquire_inflight(struct rq_wait *rqw, void *private_data)
{
struct iolatency_grp *iolat = private_data;
- return rq_wait_inc_below(rqw, iolat->rq_depth.max_depth);
+ return rq_wait_inc_below(rqw, iolat->max_depth);
}

static void __blkcg_iolatency_throttle(struct rq_qos *rqos,
@@ -372,7 +372,7 @@ static void scale_change(struct iolatency_grp *iolat, bool up)
{
unsigned long qd = iolat->blkiolat->rqos.q->nr_requests;
unsigned long scale = scale_amount(qd, up);
- unsigned long old = iolat->rq_depth.max_depth;
+ unsigned long old = iolat->max_depth;

if (old > qd)
old = qd;
@@ -384,12 +384,12 @@ static void scale_change(struct iolatency_grp *iolat, bool up)
if (old < qd) {
old += scale;
old = min(old, qd);
- iolat->rq_depth.max_depth = old;
+ iolat->max_depth = old;
wake_up_all(&iolat->rq_wait.wait);
}
} else {
old >>= 1;
- iolat->rq_depth.max_depth = max(old, 1UL);
+ iolat->max_depth = max(old, 1UL);
}
}

@@ -442,7 +442,7 @@ static void check_scale_change(struct iolatency_grp *iolat)
}

/* We're as low as we can go. */
- if (iolat->rq_depth.max_depth == 1 && direction < 0) {
+ if (iolat->max_depth == 1 && direction < 0) {
blkcg_use_delay(lat_to_blkg(iolat));
return;
}
@@ -450,7 +450,7 @@ static void check_scale_change(struct iolatency_grp *iolat)
/* We're back to the default cookie, unthrottle all the things. */
if (cur_cookie == DEFAULT_SCALE_COOKIE) {
blkcg_clear_delay(lat_to_blkg(iolat));
- iolat->rq_depth.max_depth = UINT_MAX;
+ iolat->max_depth = UINT_MAX;
wake_up_all(&iolat->rq_wait.wait);
return;
}
@@ -505,7 +505,7 @@ static void iolatency_record_time(struct iolatency_grp *iolat,
* We don't want to count issue_as_root bio's in the cgroups latency
* statistics as it could skew the numbers downwards.
*/
- if (unlikely(issue_as_root && iolat->rq_depth.max_depth != UINT_MAX)) {
+ if (unlikely(issue_as_root && iolat->max_depth != UINT_MAX)) {
u64 sub = iolat->min_lat_nsec;
if (req_time < sub)
blkcg_add_delay(lat_to_blkg(iolat), now, sub - req_time);
@@ -916,7 +916,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s)
}
preempt_enable();

- if (iolat->rq_depth.max_depth == UINT_MAX)
+ if (iolat->max_depth == UINT_MAX)
seq_printf(s, " missed=%llu total=%llu depth=max",
(unsigned long long)stat.ps.missed,
(unsigned long long)stat.ps.total);
@@ -924,7 +924,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s)
seq_printf(s, " missed=%llu total=%llu depth=%u",
(unsigned long long)stat.ps.missed,
(unsigned long long)stat.ps.total,
- iolat->rq_depth.max_depth);
+ iolat->max_depth);
}

static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)
@@ -941,12 +941,12 @@ static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)

avg_lat = div64_u64(iolat->lat_avg, NSEC_PER_USEC);
cur_win = div64_u64(iolat->cur_win_nsec, NSEC_PER_MSEC);
- if (iolat->rq_depth.max_depth == UINT_MAX)
+ if (iolat->max_depth == UINT_MAX)
seq_printf(s, " depth=max avg_lat=%llu win=%llu",
avg_lat, cur_win);
else
seq_printf(s, " depth=%u avg_lat=%llu win=%llu",
- iolat->rq_depth.max_depth, avg_lat, cur_win);
+ iolat->max_depth, avg_lat, cur_win);
}

static struct blkg_policy_data *iolatency_pd_alloc(gfp_t gfp,
@@ -990,9 +990,7 @@ static void iolatency_pd_init(struct blkg_policy_data *pd)
latency_stat_init(iolat, &iolat->cur_stat);
rq_wait_init(&iolat->rq_wait);
spin_lock_init(&iolat->child_lat.lock);
- iolat->rq_depth.queue_depth = blkg->q->nr_requests;
- iolat->rq_depth.max_depth = UINT_MAX;
- iolat->rq_depth.default_depth = iolat->rq_depth.queue_depth;
+ iolat->max_depth = UINT_MAX;
iolat->blkiolat = blkiolat;
iolat->cur_win_nsec = 100 * NSEC_PER_MSEC;
atomic64_set(&iolat->window_start, now);
--
2.30.0


2022-10-17 18:43:19

by Josef Bacik

[permalink] [raw]
Subject: Re: [PATCH 3/3] block: Replace struct rq_depth with unsigned int in struct iolatency_grp

On Thu, Sep 29, 2022 at 03:40:55PM +0800, Kemeng Shi wrote:
> We only need a max queue depth for every iolatency to limit the inflight io
> number. Replace struct rq_depth with unsigned int to simplfy "struct
> iolatency_grp" and save memory.
>
> Signed-off-by: Kemeng Shi <[email protected]>

Reviewed-by: Josef Bacik <[email protected]>

Thanks,

Josef