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From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/8] xfs: separate CIL commit record IO
Date: Thu, 25 Feb 2021 09:34:47 +0100	[thread overview]
Message-ID: <YDdhJ0Oe6R+UXqDU@infradead.org> (raw)
In-Reply-To: <20210224214417.GB4662@dread.disaster.area>

On Thu, Feb 25, 2021 at 08:44:17AM +1100, Dave Chinner wrote:
> > Also, do you have any idea what was Christoph talking about wrt devices
> > with no-op flushes the last time this patch was posted?  This change
> > seems straightforward to me (assuming the answers to my two question are
> > 'yes') but I didn't grok what subtlety he was alluding to...?
> 
> He was wondering what devices benefited from this. It has no impact
> on highspeed devices that do not require flushes/FUA (e.g. high end
> intel optane SSDs) but those are not the devices this change is
> aimed at. There are no regressions on these high end devices,
> either, so they are largely irrelevant to the patch and what it
> targets...

I don't think it is that simple.  Pretty much every device aimed at
enterprise use does not enable a volatile write cache by default.  That
also includes hard drives, arrays and NAND based SSDs.

Especially for hard drives (or slower arrays) the actual I/O wait might
matter.  What is the argument against making this conditional?

  parent reply	other threads:[~2021-02-25  8:37 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-23  3:34 [PATCH v2] xfs: various log stuff Dave Chinner
2021-02-23  3:34 ` [PATCH 1/8] xfs: log stripe roundoff is a property of the log Dave Chinner
2021-02-23 10:29   ` Chandan Babu R
2021-02-24 20:14   ` Darrick J. Wong
2021-02-25  8:32   ` Christoph Hellwig
2021-03-01 15:13   ` Brian Foster
2021-02-23  3:34 ` [PATCH 2/8] xfs: separate CIL commit record IO Dave Chinner
2021-02-23 12:12   ` Chandan Babu R
2021-02-24 20:34   ` Darrick J. Wong
2021-02-24 21:44     ` Dave Chinner
2021-02-24 23:06       ` Darrick J. Wong
2021-02-25  8:34       ` Christoph Hellwig [this message]
2021-02-25 20:47         ` Dave Chinner
2021-03-01  9:09           ` Christoph Hellwig
2021-03-03  0:11             ` Dave Chinner
2021-02-26  2:48         ` Darrick J. Wong
2021-02-28 16:36           ` Brian Foster
2021-02-28 23:46             ` Dave Chinner
2021-03-01 15:33               ` Brian Foster
2021-03-01 15:19   ` Brian Foster
2021-03-03  0:41     ` Dave Chinner
2021-03-03 15:22       ` Brian Foster
2021-03-04 22:57         ` Dave Chinner
2021-03-05  0:44       ` Dave Chinner
2021-02-23  3:34 ` [PATCH 3/8] xfs: move and rename xfs_blkdev_issue_flush Dave Chinner
2021-02-23 12:57   ` Chandan Babu R
2021-02-24 20:45   ` Darrick J. Wong
2021-02-24 22:01     ` Dave Chinner
2021-02-25  8:36   ` Christoph Hellwig
2021-02-23  3:34 ` [PATCH 4/8] xfs: async blkdev cache flush Dave Chinner
2021-02-23  5:29   ` Chaitanya Kulkarni
2021-02-23 14:02   ` Chandan Babu R
2021-02-24 20:51   ` Darrick J. Wong
2021-02-23  3:34 ` [PATCH 5/8] xfs: CIL checkpoint flushes caches unconditionally Dave Chinner
2021-02-24  7:16   ` Chandan Babu R
2021-02-24 20:57   ` Darrick J. Wong
2021-02-25  8:42   ` Christoph Hellwig
2021-02-25 21:07     ` Dave Chinner
2021-02-23  3:34 ` [PATCH 6/8] xfs: remove need_start_rec parameter from xlog_write() Dave Chinner
2021-02-24  7:17   ` Chandan Babu R
2021-02-24 20:59   ` Darrick J. Wong
2021-02-25  8:49   ` Christoph Hellwig
2021-02-25 20:55     ` Dave Chinner
2021-02-23  3:34 ` [PATCH 7/8] xfs: journal IO cache flush reductions Dave Chinner
2021-02-23  8:05   ` [PATCH 7/8 v2] " Dave Chinner
2021-02-24 12:27     ` Chandan Babu R
2021-02-24 20:32       ` Dave Chinner
2021-02-24 21:13     ` Darrick J. Wong
2021-02-24 22:03       ` Dave Chinner
2021-02-25  4:09     ` Chandan Babu R
2021-02-25  7:13       ` Chandan Babu R
2021-03-01  5:44       ` Dave Chinner
2021-03-01  5:56         ` Dave Chinner
2021-02-25  8:58     ` Christoph Hellwig
2021-02-25 21:06       ` Dave Chinner
2021-03-01 19:29     ` Brian Foster
2021-02-23  3:34 ` [PATCH 8/8] xfs: Fix CIL throttle hang when CIL space used going backwards Dave Chinner
2021-02-24 21:18   ` Darrick J. Wong
2021-02-24 22:05     ` Dave Chinner

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