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Re: [Xen-devel] Fwd: xentop reporting zero written sectors

To: Andy Burns <xen.lists@xxxxxxxxxxx>
Subject: Re: [Xen-devel] Fwd: xentop reporting zero written sectors
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Mon, 10 Oct 2011 16:29:59 +0100
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Mon, 2011-10-10 at 16:16 +0100, Andy Burns wrote:
> No response in xen-users, asking developers ....
> 
> ---------- Forwarded message ----------
> 
> Just moving a chunk of files from one filesysstem on xvba to another
> on xvdb, and was monitoring with xentop as it was taking longer than
> expected.
> 
> The VBD_RD  and VBD_WR counters were both clocking-up as expected, as
> was the VBD_RSECT counter, but the VBD_WSECT counter was stuck on
> zero, I toggled on the individual VBD device counters and these showed
> the same (with the RD and WR counters correctly split between my
> source and destination disks)
> 
> Is this a long standing "feature" that I've never noticed before or a
> problem that should be reported?

How would it be a feature?

Scrobbling around under tools/xenstat these statistics appear to be read
from /sys/bus/xen-backend/devices/<vbd>/wr_sect (likewise rd_sect,
wr_req etc etc).

Can you see all of those and do the numbers appear to be doing the right
thing? This will indicate whether this is an issue with the kernel
producing the numbers or the tools consuming them.

Ian.

> 
> Using the following packages from Fedora 16 beta
> 
> xen.x86_64                                   4.1.1-3.fc16
> en-hypervisor.x86_64                 4.1.1-3.fc16
> xen-libs.x86_64                           4.1.1-3.fc16
> xen-licenses.x86_64                  4.1.1-3.fc16
> xen-runtime.x86_64                    4.1.1-3.fc16
> kernel.x86_64                              3.1.0-0.rc8.git0.0.fc16
> 
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> http://lists.xensource.com/xen-devel



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