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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 07:40:06 -1000	[thread overview]
Message-ID: <ZpgB9kCAxAAXAtSi@slm.duckdns.org> (raw)
In-Reply-To: <f448f66b-7a91-4281-8f77-159541cbacff@redhat.com>

Hello, Waiman.

On Wed, Jul 17, 2024 at 01:37:56PM -0400, Waiman Long wrote:
> bis->sync is still being used in blk_cgroup_bio_start(). Replacing it with a
> global lock may kill performance. We may have to use a per-cpu lock if we
> want to go this route of eliminating bis->sync.

So, the idea is to keep using u64_sync for blkg->iostat_cpu and use
blkg_stat_lock for blkg->iostat. The former is the only one which is updated
in hot path, right?

Thanks.

-- 
tejun

  reply	other threads:[~2024-07-17 17:40 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 [this message]
2024-07-17 18:18               ` Waiman Long
2024-07-17 18:24                 ` tj
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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