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From: Bart Van Assche <bvanassche@acm.org>
To: Gulam Mohamed <gulam.mohamed@oracle.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V2] Consider inflight IO in io accounting for high latency devices
Date: Mon, 16 Oct 2023 14:16:09 -0700	[thread overview]
Message-ID: <d10c329b-85c9-4bc2-be00-f156c48639e5@acm.org> (raw)
In-Reply-To: <CO1PR10MB4563B1B650C89FA32B60AE1298D7A@CO1PR10MB4563.namprd10.prod.outlook.com>

On 10/16/23 13:01, Gulam Mohamed wrote:
> [GULAM]: Yes, it will be called for every submitted bio but for the
> high latency devices it will not have much impact. This is indicated
> by the latency figures I provided in the review mail, with and
> without our patch.

Calling tag iteration code from the hot path is wrong.

There are more devices than only hard disks that have a single hardware
queue, e.g. certain SSDs. I'm pretty sure that this patch will have a
significant negative performance impact for such devices.

Thanks,

Bart.

  reply	other threads:[~2023-10-16 21:16 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-13 19:55 Gulam Mohamed
2023-10-13 21:13 ` Bart Van Assche
2023-10-16 20:01   ` Gulam Mohamed
2023-10-16 21:16     ` Bart Van Assche [this message]
2023-10-17  4:13       ` Gulam Mohamed
2023-10-17 14:23         ` Jens Axboe
2023-10-18 18:44           ` Gulam Mohamed
2023-10-18 18:56             ` Jens Axboe
2023-10-19 16:44               ` Gulam Mohamed

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