Re: [Xen-devel] [RFC v1 0/5] VBD: enlarge max segment per request in blkfront

["Duan, Ronghui" <ronghui.duan@xxxxxxxxx>]

> >>> On 16.08.12 at 12:22, "Duan, Ronghui" <ronghui.duan@xxxxxxxxx> wrote:
> > The max segments for request in VBD queue is 11, while for Linux OS/
> > other VMM, the parameter is set to 128 in default. This may be caused
> > by the limited size of ring between Front/Back. So I guess whether we
> > can put segment data into another ring and dynamic use them for the
> > single request's need. Here is prototype which don't do much test, but
> > it can work on Linux 64 bits 3.4.6 kernel. I can see the CPU% can be
> > reduced to 1/3 compared to original in sequential test. But it bring
> > some overhead which will make random IO's cpu utilization increase a little.
> 
> In what way to improve blkback is intended to be subject of a discussion on 
> the
> summit - are you by any chance going to be there? Fact is that there are a
> number of other extensions to the interface, and since you don't mention those
> I'm assuming you were not aware of them.
> 
So pity that I can't be there. Indeed I did not see the other extension before.
I begin this from seeing the larger overhead in CPU in sequential IO. Then I 
try 
multiple ring and get a lot of help from Stefano. Then I have an idea adding a 
ring as
Segment separate. Stefano suggest to send here and listen for advice.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel