From: Dario Faggioli <dfaggioli@suse.com>
To: "Jürgen Groß" <jgross@suse.com>, "Julien Grall" <julien@xen.org>,
"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Jan Beulich <jbeulich@suse.com>
Subject: Re: [RFC PATCH v1 4/6] xentop: collect IRQ and HYP time statistics.
Date: Fri, 12 Jun 2020 17:29:40 +0200 [thread overview]
Message-ID: <78910b5c27a3711726d53e931feb075c5cc4a64c.camel@suse.com> (raw)
In-Reply-To: <a5d7bbe8-a9ff-1396-bd7f-3b6143bddac7@suse.com>
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On Fri, 2020-06-12 at 14:41 +0200, Jürgen Groß wrote:
> On 12.06.20 14:29, Julien Grall wrote:
> > On 12/06/2020 05:57, Jürgen Groß wrote:
> > > On 12.06.20 02:22, Volodymyr Babchuk wrote:
> > > >
> > > > @@ -994,9 +998,22 @@ s_time_t sched_get_time_correction(struct
> > > > sched_unit *u)
> > > > break;
> > > > }
> > > > + spin_lock_irqsave(&sched_stat_lock, flags);
> > > > + sched_stat_irq_time += irq;
> > > > + sched_stat_hyp_time += hyp;
> > > > + spin_unlock_irqrestore(&sched_stat_lock, flags);
> > >
> > > Please don't use a lock. Just use add_sized() instead which will
> > > add
> > > atomically.
> >
> > If we expect sched_get_time_correction to be called concurrently
> > then we
> > would need to introduce atomic64_t or a spin lock.
>
> Or we could use percpu variables and add the cpu values up when
> fetching the values.
>
Yes, either percpu or atomic looks much better than locking, to me, for
this.
Regards
--
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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next prev parent reply other threads:[~2020-06-12 15:30 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
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 [this message]
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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