On 07/03/2011 04:36 PM, Paolo Bonzini wrote:
On 07/02/2011 03:50 PM, Hannes Reinecke wrote:
(And no, I will not getting into another dog-fight with Paul B. here.
Virtio can do without bounce buffers. AHCI can. So I fail to see why
SCSI has to rely on bounce buffers.)
I agree, but I do see why a SCSI device might prefer to rely on
bounce buffers for non-I/O commands. This is why in my last RFC
series for vmw_pvscsi I let the device choose whether to force a
bounce buffer or get an external iovec from the HBA.
Yes, sure, for non-I/O commands it's perfectly okay.
Most of which will be emulated anyway.
It's bounce buffers for I/O which kills performance.
But I seem to have missed your last RFC (I'm not reading qemu-devel
on a regular basis ...).
Care to send me a pointer to it?
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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