Re: [Xen-devel] [PATCH] xen: blkif.h: document linux xen-block multi-page ring implementation

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 12/05/15 11:58, Bob Liu wrote:
> After commit 1b1586eeeb8c ("xenbus_client: Extend interface to
> support multi-page ring"), Linux xenbus driver can support multi-page ring.
> 
> Based on this interface, we got some impressive improvements by using 
> multi-page
> ring in xen-block driver. If using 64 pages as the ring, the IOPS increased
> about 15 times for the throughput testing.
> 
> The Linux implementation reuses two 'DEPRECATED' nodes('max-ring-pages' and
> 'num-ring-pages), so that nothing would be broken.
> Also removed the power of 2 limit and updated the default/max value 
> accordingly.

You can't drop the power of 2 restriction as there may be frontends that
support this old option (from before it was deprecated) and these may
not support non-powers of 2.

David


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