Re: [Xen-devel] Monitoring I/O rate for each VMs

[Nick Craig-Wood <nick@xxxxxxxxxxxxxx>]

On Mon, Nov 27, 2006 at 09:41:12AM +0000, Keir Fraser wrote:
> On 27/11/06 09:25, "Thomas Goirand" <thomas@xxxxxxxxxx> wrote:
> 
> >> Unfortunately these count requests rather than bytes served. This may be
> >> what you want though, as #requests should be proportional to the number of
> >> expensive disc operations (seeking and settling). Long contiguous requests
> >> are not proportionally more expensive than short ones.
> > 
> > I didn't find such file where you said. Even a "locate statistics"
> > didn't help. Note that I'm using lvm partitions, and xen 3.0.2-2 (and
> > 2.0.7 in some older servers), and my LVs are of form /dev/lvm1/xen01, is
> > <path-to-vdb> for loopback?

Note also, "xm top", followed by 'b' shows the same statistics.

> I think the stats were added during 3.0.3 development. There's no way to get
> the information you seek with older versions of Xen, although you could try
> taking the blkback driver from a 3.0.3 tree and build it against your Linux
> dom0 kernel.

Note that these stats don't work for tap:aio: block devices, eg

# grep disk /etc/xen/sarge1
disk = [ 'tap:aio:/home/sarge1/root_fs,sda1,w', 
'tap:aio:/home/sarge1/swap,sda2,w' ]

# xm list sarge1
Name                                      ID Mem(MiB) VCPUs State   Time(s)
sarge1                                     2      128     4 -b----     22.2

# cat /sys/block/dm-2/stat 
       0        0        0        0        0        0        0        0        
0        0        0

-- 
Nick Craig-Wood <nick@xxxxxxxxxxxxxx> -- http://www.craig-wood.com/nick

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