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From: "tj@kernel.org" <tj@kernel.org>
To: "Boy Wu (吳勃誼)" <Boy.Wu@mediatek.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"boris@bur.io" <boris@bur.io>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"cgroups@vger.kernel.org" <cgroups@vger.kernel.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 15:27:43 -1000	[thread overview]
Message-ID: <Zphvj1kXK2xcKj7J@slm.duckdns.org> (raw)
In-Reply-To: <99af713e187a92f0501482e8344be469f1b3e454.camel@mediatek.com>

Hello,

On Thu, Jul 18, 2024 at 01:21:32AM +0000, Boy Wu (吳勃誼) wrote:
...
> I think this will work, but as I mentioned before, this issue is only
> on 32 bit SMP systems. Replacing u64 sync with spinlock will increase
> overhead on 64 bit systems, because u64 sync does nothing on 64 bit
> systems. However, if it is acceptable, we can proceed with this
> solution.

We can encapsulate the spinlock in some helpers and make them conditional on
32bit. However, the u64_sync -> spinlock conversions in the suggested patch
are all on cold paths, so I doubt it'd be all that noticeable especially
given that the hottest path of them all is already grabbing blkg_stat_lock,
but either way is fine by me.

Thanks.

-- 
tejun

      reply	other threads:[~2024-07-18  1:27 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
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 [this message]

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