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RE: [Xen-devel] Interrupt levels

To: "Nicholas Lee" <nic-lists@xxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Interrupt levels
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Tue, 8 Mar 2005 23:24:56 -0000
Cc: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxxx>, <ian.pratt@xxxxxxxxxxxx>, <ian.pratt@xxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Interrupt levels
> On Tue, Mar 08, 2005 at 11:07:53AM -0000, Ian Pratt wrote:
> > Since processing timer interrupts are cheap there's no urgent fix
> > required.
> > The real question is why are you blocking/unblocking at a rate of
> > 55k/second.
> Seems to be affecting my interactive latency though. I was going to
> test a headless NX desktop install, I'll probably hold off on 
> that for a
> little while.

55k interrupts/second will certainly make things seem sluggish. 
There's something bad happening on your system.
> NFS, qmail, apache/php, imap and openvpn are the main 
> services. Very low
> load. Two imap sessions, one openvpn sessions. Not more than 
> 2000 emails
> per day.  CRM114 and clamav virus/spam scanning. mutt.
> Postgres and mysql, on very low loads.
> vmstat intr figures for the guest domU domains is usually <30.
> I'm going reduce a dom0 kernel configure to the minimal and 
> see how that
> functions.

It would be very helpful if you could see whether you can reproduce this
with just dom0, or with one of our stock 2.0-testing kernels.

I'd like to get to the bottom of this before announcing 2.0.5.


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