Re: [Xen-users] I/O issue in xen guest OS

To:	Radu Rendec <radu.rendec@xxxxxxx>
Subject:	Re: [Xen-users] I/O issue in xen guest OS
From:	chandrashekar <chanlinux@xxxxxxxxx>
Date:	Mon, 6 Jul 2009 20:40:25 +0530
Cc:	xen-users@xxxxxxxxxxxxxxxxxxx
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Radu,

Thanks for the help:

As you suggested I checked CPU % and there is no issue in CPU but I think this is issue with memory.

Please find the xm top for the same.

xentop - 20:35:49   Xen 3.1.2-92.el5
2 domains: 1 running, 1 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
Mem: 4193636k total, 4193292k used, 344k free    CPUs: 8 @ 2333MHz
NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%) VCPUS NETS NETTX(k) NETRX(k) VBDS VBD_OO VBD_RD VBD_WR SSID
Domain-0 -----r     23050    0.7    2200640   52.5   no limit       n/a     8    4      248 2101165    0        0 0        0    0
guest --b---        3938    0.0    1945432   46.4    1945600      46.4     1    1 2197321 2803970    0        0 0        0    0

~
Thanks,
Chandru

On Mon, Jul 6, 2009 at 8:05 PM, Radu Rendec <radu.rendec@xxxxxxx> wrote:

Hi,

If you have other guests that eat up CPU, perhaps your guest does not
get enough CPU to process all the data that the host is able to
transfer. What does "xm top" say about physical CPU usage?

Another possible cause may be using a slow backend for guest storage
(for instance a file over ntfs-3g mount), or the host being very busy
doing something else than I/O. This would cause lower I/O load in the
host (with more CPU load on other things), while the guest waits 100% of
the time for I/O.

Cheers,

Radu R.

On Mon, 2009-07-06 at 16:57 +0530, chandrashekar wrote:
> Hi,
>
> I have a xen guest OS and in which I am trying to copy 3GB of file
> from one location to another(say from / to /home),at this time I/O of
> the guest OS is reaching 100% and I/O of the Domain-0 is reaching up
> to 10 to 12%.
>
> How can I solve this issue.
>
> Thanks,
> Chanlinux

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Re: [Xen-users] I/O issue in xen guest OS