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Re: [Qemu-devel] [PATCH] virtio-blk: add SGI_IO passthru support


From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH] virtio-blk: add SGI_IO passthru support
Date: Mon, 27 Apr 2009 12:15:31 +0300
User-agent: Thunderbird 2.0.0.21 (X11/20090320)

Christoph Hellwig wrote:
[had the qemu list address wrong the first time, reply to this message,
 not the previous if you were on Cc]


Add support for SG_IO passthru (packet commands) to the virtio-blk
backend.  Conceptually based on an older patch from Hannes Reinecke
but largely rewritten to match the code structure and layering in
virtio-blk.

Note that currently we issue the hose SG_IO synchronously.  We could
easily switch to async I/O, but that would required either bloating
the VirtIOBlockReq by the size of struct sg_io_hdr or an additional
memory allocation for each SG_IO request.

I think that's worthwhile. The extra bloat is trivial (especially as the number of inflight virtio requests is tightly bounded), and stalling the vcpu for requests is a pain.

--
error compiling committee.c: too many arguments to function





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