From: Michael Lyle <mlyle@lyle.org>
To: tang.junhui@zte.com.cn
Cc: linux-bcache@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [for-416 PATCH 3/3] bcache: allow quick writeback when backing idle
Date: Tue, 2 Jan 2018 08:23:14 -0800 [thread overview]
Message-ID: <0fdcfaaf-af7a-adb8-075d-b321b9df4ef7@lyle.org> (raw)
In-Reply-To: <1514883236-11844-1-git-send-email-tang.junhui@zte.com.cn>
On 01/02/2018 12:53 AM, tang.junhui@zte.com.cn wrote:
> If no front-end I/O coming, would this cause write-back IOs one by one
> (one write-back IO issued must after the completion of the previous IO)?
> though with zero delay time, is the write-back performance still good?
Yes-- this speeds up writeback during idle from 4k/sec to about 10MB/sec
on my slow 5400RPM disk. (It writes back at about 20MB/sec with deep
queues in the same scenario). So in this case it's about 2500x faster
than current idle writeback, but half as fast as writeback with full
device utilization.
With only one I/O outstanding at a time, if front-end I/O starts latency
for the first request is still good.
> Thanks,
> Tang Junhui
Mike
next prev parent reply other threads:[~2018-01-02 16:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-02 8:53 [for-416 PATCH 3/3] bcache: allow quick writeback when backing idle tang.junhui
2018-01-02 16:23 ` Michael Lyle [this message]
2018-01-03 16:54 ` Coly Li
-- strict thread matches above, loose matches on Subject: below --
2018-01-02 7:02 tang.junhui
2018-01-02 8:18 ` Michael Lyle
2017-12-28 0:47 [for-416 PATCH 1/3] bcache: writeback: collapse contiguous IO better Michael Lyle
2017-12-28 0:47 ` [for-416 PATCH 3/3] bcache: allow quick writeback when backing idle Michael Lyle
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