All of lore.kernel.org
 help / color / mirror / Atom feed
From: Wei Yang <richard.weiyang@gmail.com>
To: tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org
Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	Wei Yang <richard.weiyang@gmail.com>
Subject: [PATCH 2/2] cgroup: rstat: retrieve current bstat to delta directly
Date: Sat,  8 Jan 2022 00:38:17 +0000	[thread overview]
Message-ID: <20220108003817.6619-2-richard.weiyang@gmail.com> (raw)
In-Reply-To: <20220108003817.6619-1-richard.weiyang@gmail.com>

Instead of retrieve current bstat to cur and copy it to delta, let's use
delta directly.

This saves one copy operation and has the same code convention as
propagating delta to parent.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 kernel/cgroup/rstat.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index c626d5a526c4..f66944c53613 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -314,7 +314,7 @@ static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
 {
 	struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
 	struct cgroup *parent = cgroup_parent(cgrp);
-	struct cgroup_base_stat cur, delta;
+	struct cgroup_base_stat delta;
 	unsigned seq;
 
 	/* Root-level stats are sourced from system-wide CPU stats */
@@ -324,11 +324,10 @@ static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
 	/* fetch the current per-cpu values */
 	do {
 		seq = __u64_stats_fetch_begin(&rstatc->bsync);
-		cur = rstatc->bstat;
+		delta = rstatc->bstat;
 	} while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
 
 	/* propagate percpu delta to global */
-	delta = cur;
 	cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
 	cgroup_base_stat_add(&cgrp->bstat, &delta);
 	cgroup_base_stat_add(&rstatc->last_bstat, &delta);
-- 
2.33.1


WARNING: multiple messages have this Message-ID (diff)
From: Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org,
	hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Wei Yang
	<richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: [PATCH 2/2] cgroup: rstat: retrieve current bstat to delta directly
Date: Sat,  8 Jan 2022 00:38:17 +0000	[thread overview]
Message-ID: <20220108003817.6619-2-richard.weiyang@gmail.com> (raw)
In-Reply-To: <20220108003817.6619-1-richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

Instead of retrieve current bstat to cur and copy it to delta, let's use
delta directly.

This saves one copy operation and has the same code convention as
propagating delta to parent.

Signed-off-by: Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 kernel/cgroup/rstat.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index c626d5a526c4..f66944c53613 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -314,7 +314,7 @@ static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
 {
 	struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
 	struct cgroup *parent = cgroup_parent(cgrp);
-	struct cgroup_base_stat cur, delta;
+	struct cgroup_base_stat delta;
 	unsigned seq;
 
 	/* Root-level stats are sourced from system-wide CPU stats */
@@ -324,11 +324,10 @@ static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
 	/* fetch the current per-cpu values */
 	do {
 		seq = __u64_stats_fetch_begin(&rstatc->bsync);
-		cur = rstatc->bstat;
+		delta = rstatc->bstat;
 	} while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
 
 	/* propagate percpu delta to global */
-	delta = cur;
 	cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
 	cgroup_base_stat_add(&cgrp->bstat, &delta);
 	cgroup_base_stat_add(&rstatc->last_bstat, &delta);
-- 
2.33.1


  reply	other threads:[~2022-01-08  0:38 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-08  0:38 [PATCH 1/2] cgroup: rstat: use same convention to assign cgroup_base_stat Wei Yang
2022-01-08  0:38 ` Wei Yang
2022-01-08  0:38 ` Wei Yang [this message]
2022-01-08  0:38   ` [PATCH 2/2] cgroup: rstat: retrieve current bstat to delta directly Wei Yang
2022-01-12 19:55 ` [PATCH 1/2] cgroup: rstat: use same convention to assign cgroup_base_stat Tejun Heo
2022-01-12 19:55   ` Tejun Heo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220108003817.6619-2-richard.weiyang@gmail.com \
    --to=richard.weiyang@gmail.com \
    --cc=cgroups@vger.kernel.org \
    --cc=hannes@cmpxchg.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lizefan.x@bytedance.com \
    --cc=tj@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.