Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk

On Tue, 03 Jul 2012 08:39:39 +0800, Asias He [off-list ref] wrote:

On 07/02/2012 02:41 PM, Rusty Russell wrote:

quoted

Sure, our guest merging might save us 100x as many exits as no merging.
But since we're not doing many requests, does it matter?

We can still have many requests with slow devices. The number of 
requests depends on the workload in guest. E.g. 512 IO threads in guest 
keeping doing IO.

You can have many requests outstanding.  But if the device is slow, the
rate of requests being serviced must be low.

Am I misunderstanding something?  I thought if you could have a high
rate of requests, it's not a slow device.

Cheers,
Rusty.