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From: Dario Faggioli <dario.faggioli@citrix.com>
To: George Dunlap <george.dunlap@eu.citrix.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
	"Keir (Xen.org)" <keir@xen.org>,
	Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH 4 of 6 v2] xen: tracing: report where a VCPU wakes up
Date: Mon, 17 Dec 2012 15:43:20 +0100	[thread overview]
Message-ID: <1355755400.5931.16.camel@Abyss> (raw)
In-Reply-To: <50CB84A1.1060205@eu.citrix.com>


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On Fri, 2012-12-14 at 19:57 +0000, George Dunlap wrote: 
> On 12/12/12 02:52, Dario Faggioli wrote:
> > When looking at traces, it turns out to be useful to know where a
> > waking-up VCPU is being queued. Yes, that is always the CPU where
> > it ran last, but that information can well be lost in past trace
> > records!
> 
> When you say "lost in past trace records", do you primarily mean that 
> the records themselves have been lost (due to the per-cpu trace buffers 
> filling up), or do you mean that it may be way way back and you don't 
> want to go back and find it?
> 
The latter... I'm quite lazy when looking at traces! :-P

> If the latter, I think the best thing to do would be to just augment 
> xenalyze to keep track of that information and print it when it sees the 
> wake record.
> 
I agree, I'll kill this patch for now, and investigate further solution
along the line you suggested in the future.

Thanks and Regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)



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  reply	other threads:[~2012-12-17 14:43 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-12  2:52 [PATCH 0 of 6 v2] xen: sched_credit: fix picking & tickling and also add some tracing Dario Faggioli
2012-12-12  2:52 ` [PATCH 1 of 6 v2] xen: sched_credit: improve picking up the idlal CPU for a VCPU Dario Faggioli
2012-12-12 10:04   ` Jan Beulich
2012-12-12 10:19     ` Dario Faggioli
2012-12-12 10:30       ` Jan Beulich
2012-12-12 10:38         ` Dario Faggioli
2012-12-14 19:50     ` George Dunlap
2012-12-17  8:35       ` Jan Beulich
2012-12-17 14:36         ` Dario Faggioli
2012-12-14 19:16   ` George Dunlap
2012-12-12  2:52 ` [PATCH 2 of 6 v2] xen: sched_credit: improve tickling of idle CPUs Dario Faggioli
2012-12-14 19:29   ` George Dunlap
2012-12-12  2:52 ` [PATCH 3 of 6 v2] xen: sched_credit: use current_on_cpu() when appropriate Dario Faggioli
2012-12-14 19:39   ` George Dunlap
2012-12-17 14:41     ` Dario Faggioli
2012-12-12  2:52 ` [PATCH 4 of 6 v2] xen: tracing: report where a VCPU wakes up Dario Faggioli
2012-12-14 19:57   ` George Dunlap
2012-12-17 14:43     ` Dario Faggioli [this message]
2012-12-12  2:52 ` [PATCH 5 of 6 v2] xen: tracing: introduce per-scheduler trace event IDs Dario Faggioli
2012-12-14 20:00   ` George Dunlap
2012-12-12  2:52 ` [PATCH 6 of 6 v2] xen: sched_credit: add some tracing Dario Faggioli
2012-12-14 20:05   ` George Dunlap
2012-12-17 14:45     ` Dario Faggioli

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