Re: [PATCH v1 7/7] xen-block: implement indirect descriptors

["Roger Pau Monné" <roger.pau@citrix.com>]

On 17/04/13 16:25, Konrad Rzeszutek Wilk wrote:
>>> Perhaps the xen-blkfront part of the patch should be just split out to make
>>> this easier?
>>>
>>> Perhaps what we really should have is just the 'max' value of megabytes
>>> we want to handle on the ring.
>>>
>>> As right now 32 ring requests * 32 segments = 4MB.  But if the user wants
>>> to se the max: 32 * 4096 = so 512MB (right? each request would handle now 16MB
>>> and since we have 32 of them = 512MB).
>>
>> I've just set that to something that brings a performance benefit
>> without having to map an insane number of persistent grants in blkback.
>>
>> Yes, the values are correct, but the device request queue (rq) is only
>> able to provide read requests with 64 segments or write requests with
>> 128 segments. I haven't been able to get larger requests, even when
>> setting this to 512 or higer.
> 
> What are you using to drive the requests? 'fio'?

Yes, I've tried fio with several "bs=" values, but it doesn't seem to
change the size of the underlying requests. Have you been able to get
bigger requests?