From: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
To: "jgross@suse.com" <jgross@suse.com>,
"julien@xen.org" <julien@xen.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "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>,
"dfaggioli@suse.com" <dfaggioli@suse.com>,
"jbeulich@suse.com" <jbeulich@suse.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 11:33:44 +0000 [thread overview]
Message-ID: <5bd54018f5e045816d25f686124395a1f27a2122.camel@epam.com> (raw)
In-Reply-To: <fcedf156-4ed6-c56a-482d-df2f867f7b3e@xen.org>
On Fri, 2020-06-12 at 12:29 +0100, Julien Grall wrote:
>
> On 12/06/2020 12:26, Volodymyr Babchuk wrote:
> > Hi Jurgen,
> >
> > thanks for the review
> >
> > On Fri, 2020-06-12 at 06:36 +0200, Jürgen Groß wrote:
> >
> > > On 12.06.20 02:22, Volodymyr Babchuk wrote:
> >
> > [...]
> >
> > > > +void vcpu_end_irq_handler(void)
> > > > +{
> > > > + int delta;
> > > > +
> > > > + if (is_idle_vcpu(current))
> > > > + return;
> > > > +
> > > > + ASSERT(current->irq_nesting);
> > > > +
> > > > + if ( --current->irq_nesting )
> > > > + return;
> > > > +
> > > > + /* We assume that irq handling time will not overflow int */
> > >
> > > This assumption might not hold for long running VMs.
> >
> > 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.
>
> So I think using a 64-bit value is likely safer.
Well, I wanted to use 64-bit value in the first place. But I got the
impression that atomic_t supports only 32-bit values. At least, this is
what I'm seeing in atomic.h
Am I wrong?
> Cheers,
>
next prev parent reply other threads:[~2020-06-12 11:34 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 [this message]
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
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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