From: "tj@kernel.org" <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: "Boy Wu (吳勃誼)" <Boy.Wu@mediatek.com>,
"boris@bur.io" <boris@bur.io>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
"linux-mediatek@lists.infradead.org"
<linux-mediatek@lists.infradead.org>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"Iverlin Wang (王苳霖)" <Iverlin.Wang@mediatek.com>,
"josef@toxicpanda.com" <josef@toxicpanda.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
"angelogioacchino.delregno@collabora.com"
<angelogioacchino.delregno@collabora.com>
Subject: Re: [PATCH v3] blk-cgroup: Replace u64 sync with spinlock for iostat update
Date: Wed, 17 Jul 2024 08:24:42 -1000 [thread overview]
Message-ID: <ZpgMajKn2O521H2s@slm.duckdns.org> (raw)
In-Reply-To: <134fc34c-10b8-4d00-aaca-8285efce9899@redhat.com>
Hello,
On Wed, Jul 17, 2024 at 02:18:39PM -0400, Waiman Long wrote:
> Well, it can be confusing whether we are dealing with blkg->iostat or
> blkg->iostat_cpu. In many cases, we are dealing with iostat_cpu instead of
> iostat like __blkcg_rstat_flush() and blkg_clear_stat(). So we can't
> eliminate the use of u64_stats_update_begin_irqsave() in those cases.
I mean, we need to distinguish them. For 32bits, blkg->iostat has multiple
updaters, so we can't use u64_sync; however, blkg->iostat_cpu has only one
updater (except blkg_clear_stat() which I don't think we need to worry too
much about), so u64_sync is fine.
Thanks.
--
tejun
next prev parent reply other threads:[~2024-07-17 18:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-16 7:52 [PATCH v3] blk-cgroup: Replace u64 sync with spinlock for iostat update boy.wu
2024-07-16 21:13 ` Tejun Heo
2024-07-17 2:25 ` Boy Wu (吳勃誼)
2024-07-17 3:44 ` Boy Wu (吳勃誼)
2024-07-17 4:09 ` Boy Wu (吳勃誼)
2024-07-17 16:55 ` tj
2024-07-17 17:37 ` Waiman Long
2024-07-17 17:40 ` tj
2024-07-17 18:18 ` Waiman Long
2024-07-17 18:24 ` tj [this message]
2024-07-17 18:55 ` Waiman Long
2024-07-17 18:57 ` tj
2024-07-18 1:21 ` Boy Wu (吳勃誼)
2024-07-18 1:27 ` tj
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