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From: Gionatan Danti <g.danti@assyoma.it>
To: linux-xfs@vger.kernel.org
Cc: g.danti@assyoma.it
Subject: Block size and read-modify-write
Date: Fri, 29 Dec 2017 00:14:14 +0100	[thread overview]
Message-ID: <021d36d95a9de952ddd38cc56d18df4f@assyoma.it> (raw)

Hi list,
I would ask a question: how XFS block size affect read-modify-write in 
case of very small writes?

For example, suppose an XFS filesystem with the default 4K data block 
size. Am I correct saying that:
- a 512B normal, cached writes will cause a read-modify-write of the 
entire 4K sector?
- a 512B O_DIRECT write will *not* cause a read-modify-write of the 4K 
sector, rather it will be flushed to disk as-is (512 bytes in length)?

Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8

             reply	other threads:[~2017-12-28 23:19 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-28 23:14 Gionatan Danti [this message]
2018-01-02 10:25 ` Block size and read-modify-write Carlos Maiolino
2018-01-03  1:19   ` Dave Chinner
2018-01-03  8:19     ` Carlos Maiolino
2018-01-03 14:54     ` Gionatan Danti
2018-01-03 21:47       ` Dave Chinner
2018-01-03 22:09         ` Gionatan Danti
2018-01-03 22:59           ` Dave Chinner
2018-01-04  1:38             ` Gionatan Danti

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