linux-kernel - RE: [PATCH] /dev/zero: also implement ->read

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Message-ID: <3b0b58be4b844162b73db1b108a9b995@AcuMS.aculab.com>
Date:   Thu, 3 Sep 2020 21:35:00 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Christophe Leroy' <christophe.leroy@...roup.eu>,
        Christoph Hellwig <hch@....de>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] /dev/zero: also implement ->read

From: Christophe Leroy
> 
> 
> Le 03/09/2020 à 17:59, Christoph Hellwig a écrit :
> > Christophe reported a major speedup due to avoiding the iov_iter
> > overhead, so just add this trivial function.  Note that /dev/zero
> > already implements both an iter and non-iter writes so this just
> > makes it more symmetric.
> >
> > Christophe Leroy <christophe.leroy@...roup.eu>
> > Signed-off-by: Christoph Hellwig <hch@....de>
> 
> Tested-by: Christophe Leroy <christophe.leroy@...roup.eu>

Any idea what has happened to make the 'iter' version so bad?

	David

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