Re: [Qemu-devel] Windows and I/O size

[Peter Lieven]

Am 08.01.2013 um 10:29 schrieb Vadim Rozenfeld <address@hidden>:

> On Tuesday, January 08, 2013 10:53:44 AM Peter Lieven wrote:
>> Am 08.01.2013 um 09:50 schrieb Vadim Rozenfeld <address@hidden>:
>>> On Tuesday, January 08, 2013 10:16:48 AM Peter Lieven wrote:
>>>> Hi all,
>>>> 
>>>> I came across the fact that Windows seems to requests greater 64KB into
>>>> pieces leading to a lot of IOPs on the storage side.
>>>> 
>>>> Can anyone imagine of a way to merge them before sending them to e.g. an
>>>> iSCSI Storage? 64KB I/O Size is not optimal when e.g. large sequential
>>>> operations with an iSCSI target.
>>>> 
>>>> Thank you,
>>>> Peter
>>> 
>>> Hi Peter.
>>> Is it viostor? Which version? The most recent one is able to handle 256K
>>> blocks.
>> 
>> Not the recent. I will try 0.1.49 now.
>> 
>> 256KB is still not that much but definitely better than 64KB. are this
>> windows limits?
> 
> not exactly. it came from the driver itself. actually, with indirect buffer 
> support in virtio the sky is the limit.  

is indirect buffering supported on all windows platforms?

Peter

> 
>> 
>> I have found docs in the net that windows splits up everything into 64kB
>> requests. Is this info old?
>> 
>> thank you,
>> Peter
>> 
>>> Best regards,
>>> Vadim.