From: Julien Grall <julien.grall.oss@gmail.com>
To: Dario Faggioli <dfaggioli@suse.com>
Cc: "jgross@suse.com" <jgross@suse.com>,
"sstabellini@kernel.org" <sstabellini@kernel.org>,
"wl@xen.org" <wl@xen.org>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"ian.jackson@eu.citrix.com" <ian.jackson@eu.citrix.com>,
"george.dunlap@citrix.com" <george.dunlap@citrix.com>,
"jbeulich@suse.com" <jbeulich@suse.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
"roger.pau@citrix.com" <roger.pau@citrix.com>
Subject: Re: [RFC PATCH v1 1/6] sched: track time spent in IRQ handler
Date: Fri, 12 Jun 2020 23:54:59 +0100 [thread overview]
Message-ID: <CAJ=z9a2efn4jvfdjavaE-mkF0nRj5XijcBJX1b+RokcQuBjjsA@mail.gmail.com> (raw)
In-Reply-To: <0fc7034d696bbc601ccf2bd563ef9fb435499eea.camel@suse.com>
On Fri, 12 Jun 2020 at 21:08, Dario Faggioli <dfaggioli@suse.com> wrote:
>
> On Fri, 2020-06-12 at 13:21 +0100, Julien Grall wrote:
> > On 12/06/2020 12:33, Volodymyr Babchuk wrote:
> > > On Fri, 2020-06-12 at 12:29 +0100, Julien Grall wrote:
> > > > > Basically, this value holds time span between calls to
> > > > > schedule(). This
> > > > > variable gets zeroed out every time scheduler requests for time
> > > > > adjustment value. So, it should not depend on total VM run
> > > > > time.
> > > > This is assuming that the scheduler will be called. With the NULL
> > > > scheduler in place, there is a fair chance this may never be
> > > > called.
> > > >
> >
> Yeah, this is a good point. I mean, I wouldn't be sure about "never",
> as even there, we'd probably have softirqs, tasklets, etc... And I
> still have to look at these patches in more details to figure out
> properly whether they'd help for this.
Unlike x86, Xen doesn't prod another pCPU consistently. :) This was
already discussed in multiple threads in the past (see [1] which not
resolved yet).
So yes, I am pretty confident I can recreate a case where the
scheduling function may never be called on Arm :).
Cheers,
[1] 315740e1-3591-0e11-923a-718e06c36445@arm.com
next prev parent reply other threads:[~2020-06-12 22:55 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 0:22 [RFC PATCH v1 0/6] Fair scheduling Volodymyr Babchuk
2020-06-12 0:22 ` [RFC PATCH v1 2/6] sched: track time spent in hypervisor tasks Volodymyr Babchuk
2020-06-12 4:43 ` Jürgen Groß
2020-06-12 11:30 ` Volodymyr Babchuk
2020-06-12 11:40 ` Jürgen Groß
2020-09-24 18:08 ` Volodymyr Babchuk
2020-09-25 17:22 ` Dario Faggioli
2020-09-25 20:21 ` Volodymyr Babchuk
2020-09-25 21:42 ` Dario Faggioli
2020-06-16 10:10 ` Jan Beulich
2020-06-18 2:50 ` Volodymyr Babchuk
2020-06-18 6:34 ` Jan Beulich
2020-06-12 0:22 ` [RFC PATCH v1 1/6] sched: track time spent in IRQ handler Volodymyr Babchuk
2020-06-12 4:36 ` Jürgen Groß
2020-06-12 11:26 ` Volodymyr Babchuk
2020-06-12 11:29 ` Julien Grall
2020-06-12 11:33 ` Volodymyr Babchuk
2020-06-12 12:21 ` Julien Grall
2020-06-12 20:08 ` Dario Faggioli
2020-06-12 22:25 ` Volodymyr Babchuk
2020-06-12 22:54 ` Julien Grall [this message]
2020-06-16 10:06 ` Jan Beulich
2020-06-12 0:22 ` [RFC PATCH v1 3/6] sched, credit2: improve scheduler fairness Volodymyr Babchuk
2020-06-12 4:51 ` Jürgen Groß
2020-06-12 11:38 ` Volodymyr Babchuk
2020-06-12 0:22 ` [RFC PATCH v1 5/6] tools: xentop: show time spent in IRQ and HYP states Volodymyr Babchuk
2020-06-12 0:22 ` [RFC PATCH v1 6/6] trace: add fair scheduling trace events Volodymyr Babchuk
2020-06-12 0:22 ` [RFC PATCH v1 4/6] xentop: collect IRQ and HYP time statistics Volodymyr Babchuk
2020-06-12 4:57 ` Jürgen Groß
2020-06-12 11:44 ` Volodymyr Babchuk
2020-06-12 12:45 ` Julien Grall
2020-06-12 22:16 ` Volodymyr Babchuk
2020-06-18 20:24 ` Volodymyr Babchuk
2020-06-18 20:34 ` Julien Grall
2020-06-18 23:35 ` Volodymyr Babchuk
2020-06-12 12:29 ` Julien Grall
2020-06-12 12:41 ` Jürgen Groß
2020-06-12 15:29 ` Dario Faggioli
2020-06-12 22:27 ` Volodymyr Babchuk
2020-06-13 6:22 ` Jürgen Groß
2020-06-18 2:58 ` Volodymyr Babchuk
2020-06-18 15:17 ` Julien Grall
2020-06-18 15:23 ` Jan Beulich
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