From: Avi Kivity <avi@redhat.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC 1/2] pci-dma-api-v1
Date: Sat, 29 Nov 2008 21:48:22 +0200 [thread overview]
Message-ID: <49319C86.8050408@redhat.com> (raw)
In-Reply-To: <f43fc5580811271114u7ecc3277kc7518fb7dbf9b4c0@mail.gmail.com>
Blue Swirl wrote:
> The previous similar attempt by Anthony for generic DMA using vectored
> IO was abandoned because the malloc/free overhead was more than the
> performance gain. Have you made any performance measurements? How does
> this version compare to the previous ones?
>
>
The pointers you gave don't blame malloc/free, instead the lack of aio
readv/writev.
Since Andrea's patches contain emulation for aio readv/writev, the
performance degradation will not occur (though we will not see the
benefit either).
I doubt you can get measure malloc overhead with anything less a
thousand disks (even there, other overheads are likely to drown that
malloc).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2008-11-29 19:48 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-27 12:35 [Qemu-devel] [RFC 1/2] pci-dma-api-v1 Andrea Arcangeli
2008-11-27 12:43 ` [Qemu-devel] [RFC 2/2] bdrv_aio_readv/writev_em Andrea Arcangeli
2008-11-28 11:09 ` Jamie Lokier
2008-11-27 19:14 ` [Qemu-devel] [RFC 1/2] pci-dma-api-v1 Blue Swirl
2008-11-28 1:56 ` Andrea Arcangeli
2008-11-28 17:59 ` Blue Swirl
2008-11-28 18:50 ` Andrea Arcangeli
2008-11-28 19:03 ` Blue Swirl
2008-11-28 19:18 ` Jamie Lokier
2008-11-29 19:49 ` Avi Kivity
2008-11-30 17:20 ` Andrea Arcangeli
2008-11-30 22:31 ` Anthony Liguori
2008-11-30 18:04 ` Andrea Arcangeli
2008-11-30 17:41 ` [Qemu-devel] [RFC 1/1] pci-dma-api-v2 Andrea Arcangeli
2008-11-30 18:36 ` [Qemu-devel] " Blue Swirl
2008-11-30 19:04 ` Andrea Arcangeli
2008-11-30 19:11 ` Blue Swirl
2008-11-30 19:20 ` Andrea Arcangeli
2008-11-30 21:36 ` Blue Swirl
2008-11-30 22:54 ` Anthony Liguori
2008-11-30 22:50 ` [Qemu-devel] " Anthony Liguori
2008-12-01 9:41 ` Avi Kivity
2008-12-01 16:37 ` Anthony Liguori
2008-12-02 9:45 ` Avi Kivity
2008-11-30 22:38 ` [Qemu-devel] [RFC 1/2] pci-dma-api-v1 Anthony Liguori
2008-11-30 22:51 ` Jamie Lokier
2008-11-30 22:34 ` Anthony Liguori
2008-11-29 19:48 ` Avi Kivity [this message]
2008-11-30 17:29 ` Andrea Arcangeli
2008-11-30 20:27 ` Avi Kivity
2008-11-30 22:33 ` Andrea Arcangeli
2008-11-30 22:33 ` Anthony Liguori
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