From: Dario Faggioli <dario.faggioli@citrix.com>
To: George Dunlap <george.dunlap@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>
Cc: george.dunlap@eu.citrix.com, edgar.iglesias@xilinx.com,
julien.grall@arm.com, xen-devel@lists.xen.org
Subject: Re: Xen on ARM IRQ latency and scheduler overhead
Date: Mon, 20 Feb 2017 12:40:06 +0100 [thread overview]
Message-ID: <1487590806.6732.197.camel@citrix.com> (raw)
In-Reply-To: <ad43d06c-8536-a0f0-6e5e-fa17b8273d4a@citrix.com>
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On Mon, 2017-02-20 at 11:04 +0000, George Dunlap wrote:
> On 18/02/17 00:41, Stefano Stabellini wrote:
> >
> > On Fri, 17 Feb 2017, Dario Faggioli wrote:
> > > cyclictest 1us cyclictest 1ms cyclictest
> > > 100ms
> > > (cycles) Credit1 Credit2 Credit1 Cred
> > > it2 Credit1 Credit2
> > > wakeup-avg 2429 2035 1980 1633
> > > 2535 1979
> > > wakeup-max 14577 113682 15153 203136
> > > 12285 115164
> >
> > I am not that familiar with the x86 side of things, but the 113682
> > and
> > 203136 look worrisome, especially considering that credit1 doesn't
> > have
> > them.
>
> Dario,
>
> Do you reckon those 'MAX' values could be the load balancer running
> (both for credit1 and credit2)?
>
If they were max-es of do_schedule, that would have been my first
guess. But not in this case, as the load balancer is never called
during wakeup (neither in Credit nor Credit2).
But I'm curious about what happen, and am going to investigate that. It
should not be too hard has: 1) looks reproducible on my (x86) testbox
that I have here; 2) since it's x86 I have tracing! :-P
Dario
--
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
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prev parent reply other threads:[~2017-02-20 11:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-10 0:54 Xen on ARM IRQ latency and scheduler overhead Stefano Stabellini
2017-02-10 8:40 ` Dario Faggioli
2017-02-10 18:32 ` Stefano Stabellini
2017-02-16 12:20 ` Dario Faggioli
2017-02-16 19:52 ` Stefano Stabellini
2017-02-16 23:07 ` Stefano Stabellini
2017-02-17 11:02 ` Dario Faggioli
2017-02-17 19:34 ` Julien Grall
2017-02-17 23:14 ` Stefano Stabellini
2017-02-18 0:02 ` Stefano Stabellini
2017-02-18 0:47 ` Dario Faggioli
2017-02-17 18:40 ` Dario Faggioli
2017-02-17 19:44 ` Julien Grall
2017-02-17 22:55 ` Stefano Stabellini
2017-02-18 0:59 ` Dario Faggioli
2017-02-20 12:18 ` Punit Agrawal
2017-02-18 0:41 ` Stefano Stabellini
2017-02-20 11:04 ` George Dunlap
2017-02-20 11:40 ` Dario Faggioli [this message]
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