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Date: Thu, 22 Nov 2012 10:52:27 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3 09/12] iov: add iov_get_ptr() to
	reference vector data
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, dkoch@cloudswitch.com, qemu-devel@nongnu.org, Michael Roth <mdroth@linux.vnet.ibm.com>, Blue Swirl <blauwirbel@gmail.com>, khoa@us.ibm.com, Stefan Hajnoczi <stefanha@redhat.com>, Asias He <asias@redhat.com>

Il 22/11/2012 10:45, Michael S. Tsirkin ha scritto:
> All this looks suspiciously like premature optimization to me.
> Do we have data to show avoiding header copy is a win?

The code is a little simpler, because we know the footer is 1 byte only.

Paolo

> The caller would have to handle the case where the header is not
> contigious, which seems just too complex - in practice the code
> seems to simply fail in this case.
> 
> Why not just copy the header using iov_from_buf()/iov_to_buf()
> and be done with it?