Re: [Xen-devel] Trace Disk I/O per guest domain!

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Sep 01, 2009 at 12:19:33AM +0530, Ata Bohra wrote:
> 
> Dear All, 
> 
>  
> 
> I am trying to trace all the disk I/O accesses made by the xen guest domains 
> to dom0 domain. I would request for critics or comments in doing the same. 
> Its easy to run "iostat -x" on all domains and dom0 to get the disk i/o 
> utilization stats, but I am just looking if there can be any other way than 
> running this utility in all domUs but using simply dom0 to get all guest 
> domain stats along with dom0 accesses (different from domUs) also. 
> 

The way we did it (VirtualIron) in the past to narrow down a specific problem 
[1] was to
instrument the blkback.c. Each time a bio was submitted we would add it to a 
list
along with the domid. And obviously in the bio_endio callback this entry would 
be
removed.

>From there on, you can add SysFS interfaces to keep track of how much I/O is 
>going
from/to each domain.

[1]: http://lists.xensource.com/archives/html/xen-devel/2008-12/msg00222.html

Oh way, you said "utility." Umm.. blktrace, but that still doesn't give you the
granularity you want.

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