From: Anthony Liguori <aliguori@us.ibm.com>
To: Blue Swirl <blauwirbel@gmail.com>
Cc: kvm-devel@lists.sourceforge.net,
Marcelo Tosatti <marcelo@kvack.org>,
qemu-devel@nongnu.org, Aurelien Jarno <aurelien@aurel32.net>,
Paul Brook <paul@codesourcery.com>
Subject: Re: [kvm-devel] [Qemu-devel] [PATCH 1/5] PCI DMA API (v3)
Date: Sun, 20 Apr 2008 14:29:43 -0500 [thread overview]
Message-ID: <480B99A7.5050207@us.ibm.com> (raw)
In-Reply-To: <f43fc5580804192342h1a2970d1pb9dcfa92b9473a0f@mail.gmail.com>
Blue Swirl wrote:
> On 4/19/08, Anthony Liguori <anthony@codemonkey.ws> wrote:
>
> Well, the IOVector part and bdrv_readv look OK, except for the heavy
> mallocing involved.
>
I don't think that in practice, malloc is going to have any sort of
performance impact. If it does, it's easy enough to implement a small
object allocator for common, small vector sizes.
> I'm not so sure about the DMA side and how everything fits together
> for zero-copy IO. For example, do we still need explicit translation
> at some point?
I'm thinking that zero copy will be implemented by setting the map and
unmap functions to NULL by default (instead of to the PCI read/write
functions). Then the bus can decide whether copy functions are needed.
I'll send an updated patch series tomorrow that includes this functionality.
Regards,
Anthony Liguori
prev parent reply other threads:[~2008-04-20 19:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-15 22:11 [Qemu-devel] [PATCH 1/5] PCI DMA API (v3) Anthony Liguori
2008-04-15 22:11 ` [Qemu-devel] [PATCH 2/5] virtio for QEMU (v3) Anthony Liguori
2008-04-15 22:11 ` [Qemu-devel] [PATCH 3/5] virtio network driver (v3) Anthony Liguori
2008-04-15 22:11 ` [Qemu-devel] [PATCH 4/5] virtio block " Anthony Liguori
2008-04-15 22:11 ` [Qemu-devel] [PATCH 5/5] virtio balloon " Anthony Liguori
2008-04-16 19:51 ` [Qemu-devel] [PATCH 1/5] PCI DMA API (v3) Blue Swirl
2008-04-16 19:54 ` Anthony Liguori
2008-04-17 19:27 ` Blue Swirl
2008-04-17 20:05 ` Anthony Liguori
2008-04-19 19:40 ` Blue Swirl
2008-04-19 20:02 ` [kvm-devel] " Anthony Liguori
2008-04-20 6:42 ` Blue Swirl
2008-04-20 19:29 ` Anthony Liguori [this message]
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