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Date:   Thu, 19 Oct 2023 23:06:42 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Catherine Hoang <catherine.hoang@oracle.com>,
        linux-xfs@vger.kernel.org
Subject: Re: [PATCH v4] xfs: allow read IO and FICLONE to run concurrently
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On Thu, Oct 19, 2023 at 01:04:11PM -0700, Darrick J. Wong wrote:
> Well... the stupid answer is that I augmented generic/176 to try to race
> buffered and direct reads with cloning a million extents and print out
> when the racing reads completed.  On an unpatched kernel, the reads
> don't complete until the reflink does:

> So as you can see, reads from the reflink source file no longer
> experience a giant latency spike.  I also wrote an fstest to check this
> behavior; I'll attach it as a separate reply.

Nice.  I guess write latency doesn't really matter for this use
case?