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Date:   Mon, 21 Sep 2020 18:12:24 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     David Laight <David.Laight@aculab.com>,
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Subject: Re: [PATCH 02/11] mm: call import_iovec() instead of
 rw_copy_check_uvector() in process_vm_rw()
Message-ID: <20200921161224.GA24807@lst.de>
References: <20200921143434.707844-1-hch@lst.de> <20200921143434.707844-3-hch@lst.de> <20200921150211.GS3421308@ZenIV.linux.org.uk> <ef67787edb2f48548d69caaaff6997ba@AcuMS.aculab.com> <20200921152937.GX3421308@ZenIV.linux.org.uk>
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On Mon, Sep 21, 2020 at 04:29:37PM +0100, Al Viro wrote:
> On Mon, Sep 21, 2020 at 03:21:35PM +0000, David Laight wrote:
> 
> > You really don't want to be looping through the array twice.
> 
> Profiles, please.

Given that the iov array should be cache hot I'd be surprised to
see a huge difference.