From: Jens Axboe <axboe@kernel.dk>
To: Shaohua Li <shli@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH]block: make auto block plug flush threshold per-disk based
Date: Fri, 06 Apr 2012 11:39:09 -0600 [thread overview]
Message-ID: <4F7F2A3D.3010700@kernel.dk> (raw)
In-Reply-To: <4F7F2765.3090003@kernel.org>
On 2012-04-06 11:27, Shaohua Li wrote:
> We do auto block plug flush to reduce latency, the threshold is 16
> requests. This works well if the task is accessing one or two drives.
> The problem is if the task is accessing a raid 0 device and the raid
> disk number is big, say 8 or 16, 16/8 = 2 or 16/16=1, we will have
> heavy lock contention.
>
> This patch makes the threshold per-disk based. The latency should be
> still ok accessing one or two drives. The setup with application
> accessing a lot of drives in the meantime uaually is big machine,
> avoiding lock contention is more important, because any contention
> will actually increase latency.
Thanks, applied. It should have been per-queue all along, so this
makes a lot of sense.
--
Jens Axboe
next prev parent reply other threads:[~2012-04-06 17:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-06 17:27 [PATCH]block: make auto block plug flush threshold per-disk based Shaohua Li
2012-04-06 17:39 ` Jens Axboe [this message]
2012-04-09 14:13 ` Jeff Moyer
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