blk-iocost: combine local_stat and desc_stat to stat

When we flush usage, wait, indebt stat in iocg_flush_stat(), we use
local_stat and desc_stat, which has no point since the leaf iocg
only has local_stat and the inner iocg only has desc_stat. Also
we don't need to flush percpu abs_vusage for these inner iocgs.

This patch combine local_stat and desc_stat to stat, only flush
percpu abs_vusage for active leaf iocgs, then build inner walk
list to propagate.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220510034757.21761-1-zhouchengming@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 70a0a3d..bf83288 100644 (file)
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -533,8 +533,7 @@ struct ioc_gq {
 
        /* statistics */
        struct iocg_pcpu_stat __percpu  *pcpu_stat;
-       struct iocg_stat                local_stat;
-       struct iocg_stat                desc_stat;
+       struct iocg_stat                stat;
        struct iocg_stat                last_stat;
        u64                             last_stat_abs_vusage;
        u64                             usage_delta_us;
@@ -1371,7 +1370,7 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
                return true;
        } else {
                if (iocg->indelay_since) {
-                       iocg->local_stat.indelay_us += now->now - iocg->indelay_since;
+                       iocg->stat.indelay_us += now->now - iocg->indelay_since;
                        iocg->indelay_since = 0;
                }
                iocg->delay = 0;
@@ -1419,7 +1418,7 @@ static void iocg_pay_debt(struct ioc_gq *iocg, u64 abs_vpay,
 
        /* if debt is paid in full, restore inuse */
        if (!iocg->abs_vdebt) {
-               iocg->local_stat.indebt_us += now->now - iocg->indebt_since;
+               iocg->stat.indebt_us += now->now - iocg->indebt_since;
                iocg->indebt_since = 0;
 
                propagate_weights(iocg, iocg->active, iocg->last_inuse,
@@ -1513,7 +1512,7 @@ static void iocg_kick_waitq(struct ioc_gq *iocg, bool pay_debt,
 
        if (!waitqueue_active(&iocg->waitq)) {
                if (iocg->wait_since) {
-                       iocg->local_stat.wait_us += now->now - iocg->wait_since;
+                       iocg->stat.wait_us += now->now - iocg->wait_since;
                        iocg->wait_since = 0;
                }
                return;
@@ -1641,11 +1640,30 @@ static void iocg_build_inner_walk(struct ioc_gq *iocg,
        }
 }
 
+/* propagate the deltas to the parent */
+static void iocg_flush_stat_upward(struct ioc_gq *iocg)
+{
+       if (iocg->level > 0) {
+               struct iocg_stat *parent_stat =
+                       &iocg->ancestors[iocg->level - 1]->stat;
+
+               parent_stat->usage_us +=
+                       iocg->stat.usage_us - iocg->last_stat.usage_us;
+               parent_stat->wait_us +=
+                       iocg->stat.wait_us - iocg->last_stat.wait_us;
+               parent_stat->indebt_us +=
+                       iocg->stat.indebt_us - iocg->last_stat.indebt_us;
+               parent_stat->indelay_us +=
+                       iocg->stat.indelay_us - iocg->last_stat.indelay_us;
+       }
+
+       iocg->last_stat = iocg->stat;
+}
+
 /* collect per-cpu counters and propagate the deltas to the parent */
-static void iocg_flush_stat_one(struct ioc_gq *iocg, struct ioc_now *now)
+static void iocg_flush_stat_leaf(struct ioc_gq *iocg, struct ioc_now *now)
 {
        struct ioc *ioc = iocg->ioc;
-       struct iocg_stat new_stat;
        u64 abs_vusage = 0;
        u64 vusage_delta;
        int cpu;
@@ -1661,34 +1679,9 @@ static void iocg_flush_stat_one(struct ioc_gq *iocg, struct ioc_now *now)
        iocg->last_stat_abs_vusage = abs_vusage;
 
        iocg->usage_delta_us = div64_u64(vusage_delta, ioc->vtime_base_rate);
-       iocg->local_stat.usage_us += iocg->usage_delta_us;
-
-       /* propagate upwards */
-       new_stat.usage_us =
-               iocg->local_stat.usage_us + iocg->desc_stat.usage_us;
-       new_stat.wait_us =
-               iocg->local_stat.wait_us + iocg->desc_stat.wait_us;
-       new_stat.indebt_us =
-               iocg->local_stat.indebt_us + iocg->desc_stat.indebt_us;
-       new_stat.indelay_us =
-               iocg->local_stat.indelay_us + iocg->desc_stat.indelay_us;
-
-       /* propagate the deltas to the parent */
-       if (iocg->level > 0) {
-               struct iocg_stat *parent_stat =
-                       &iocg->ancestors[iocg->level - 1]->desc_stat;
-
-               parent_stat->usage_us +=
-                       new_stat.usage_us - iocg->last_stat.usage_us;
-               parent_stat->wait_us +=
-                       new_stat.wait_us - iocg->last_stat.wait_us;
-               parent_stat->indebt_us +=
-                       new_stat.indebt_us - iocg->last_stat.indebt_us;
-               parent_stat->indelay_us +=
-                       new_stat.indelay_us - iocg->last_stat.indelay_us;
-       }
+       iocg->stat.usage_us += iocg->usage_delta_us;
 
-       iocg->last_stat = new_stat;
+       iocg_flush_stat_upward(iocg);
 }
 
 /* get stat counters ready for reading on all active iocgs */
@@ -1699,13 +1692,13 @@ static void iocg_flush_stat(struct list_head *target_iocgs, struct ioc_now *now)
 
        /* flush leaves and build inner node walk list */
        list_for_each_entry(iocg, target_iocgs, active_list) {
-               iocg_flush_stat_one(iocg, now);
+               iocg_flush_stat_leaf(iocg, now);
                iocg_build_inner_walk(iocg, &inner_walk);
        }
 
        /* keep flushing upwards by walking the inner list backwards */
        list_for_each_entry_safe_reverse(iocg, tiocg, &inner_walk, walk_list) {
-               iocg_flush_stat_one(iocg, now);
+               iocg_flush_stat_upward(iocg);
                list_del_init(&iocg->walk_list);
        }
 }
@@ -2152,16 +2145,16 @@ static int ioc_check_iocgs(struct ioc *ioc, struct ioc_now *now)
 
                /* flush wait and indebt stat deltas */
                if (iocg->wait_since) {
-                       iocg->local_stat.wait_us += now->now - iocg->wait_since;
+                       iocg->stat.wait_us += now->now - iocg->wait_since;
                        iocg->wait_since = now->now;
                }
                if (iocg->indebt_since) {
-                       iocg->local_stat.indebt_us +=
+                       iocg->stat.indebt_us +=
                                now->now - iocg->indebt_since;
                        iocg->indebt_since = now->now;
                }
                if (iocg->indelay_since) {
-                       iocg->local_stat.indelay_us +=
+                       iocg->stat.indelay_us +=
                                now->now - iocg->indelay_since;
                        iocg->indelay_since = now->now;
                }