From: Dario Faggioli <dfaggioli@suse.com>
To: "andrii.anisov@gmail.com" <andrii.anisov@gmail.com>,
Juergen Gross <JGross@suse.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "sstabellini@kernel.org" <sstabellini@kernel.org>,
"andrii_anisov@epam.com" <andrii_anisov@epam.com>,
"george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"tim@xen.org" <tim@xen.org>,
"julien.grall@arm.com" <julien.grall@arm.com>,
Jan Beulich <JBeulich@suse.com>
Subject: Re: [Xen-devel] [RFC 0/6] XEN scheduling hardening
Date: Mon, 29 Jul 2019 18:46:06 +0000 [thread overview]
Message-ID: <522ba57b26c27875c34a153e101b3958ec8dd451.camel@suse.com> (raw)
In-Reply-To: <30bb656e-fe48-e92e-403c-efc8fb7e8cb7@gmail.com>
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On Mon, 2019-07-29 at 17:47 +0300, Andrii Anisov wrote:
> On 26.07.19 15:14, Juergen Gross wrote:
> > > >
> > Tasklets are sometimes used to perform async actions which can't be
> > done
> > in guest vcpu context.
> > [...]
> > Like switching a domain to shadow mode for L1TF
> > mitigation,
>
> Sorry I'm not really aware what L1TF mitigation is.
> But
>
> > or marshalling all cpus for stop_machine().
>
> I think I faced some time ago. When fixed a noticeable lag in video
> playback at the moment of the other domain reboot.
>
No, stop_machine() is not about a VM being shutdown/killed/stopped.
It's, let's say, about all the (physical) CPU in the host having to do
something, in a coordinated way.
Check the comment in xen/include/xen/stop_machine.h
> > You don't want
> > to be able to block tasklets, you want them to run as soon as
> > possible.
>
> Should it really be done in the way of breaking scheduling? What if
> the system has RT requirements?
>
It's possible, I guess, that we can implement some of the things that
are done in tasklets (either stop_machine() or something else)
differently, and in a way that is less disruptive for scheduling and
determinism.
But, if it is, it's not going to be as easy as <<let's run tasklet at
domain priority, and be done with it>>, I'm afraid. :-(
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:[~2019-07-29 18:47 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 10:37 [Xen-devel] [RFC 0/6] XEN scheduling hardening Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 1/6] xen/arm: Re-enable interrupt later in the trap path Andrii Anisov
2019-07-26 10:48 ` Julien Grall
2019-07-30 17:35 ` Andrii Anisov
2019-07-30 20:10 ` Julien Grall
2019-08-01 6:45 ` Andrii Anisov
2019-08-01 9:37 ` Julien Grall
2019-08-02 8:28 ` Andrii Anisov
2019-08-02 9:03 ` Julien Grall
2019-08-02 12:24 ` Andrii Anisov
2019-08-02 13:22 ` Julien Grall
2019-08-01 11:19 ` Dario Faggioli
2019-08-02 7:50 ` Andrii Anisov
2019-08-02 9:15 ` Julien Grall
2019-08-02 13:07 ` Andrii Anisov
2019-08-02 13:49 ` Julien Grall
2019-08-03 1:39 ` Dario Faggioli
2019-08-03 0:55 ` Dario Faggioli
2019-08-06 13:09 ` Andrii Anisov
2019-08-08 14:07 ` Andrii Anisov
2019-08-13 14:45 ` Dario Faggioli
2019-08-15 18:25 ` Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 2/6] schedule: account true system idle time Andrii Anisov
2019-07-26 12:00 ` Dario Faggioli
2019-07-26 12:42 ` Andrii Anisov
2019-07-29 11:40 ` Dario Faggioli
2019-08-01 8:23 ` Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 3/6] sysctl: extend XEN_SYSCTL_getcpuinfo interface Andrii Anisov
2019-07-26 12:15 ` Dario Faggioli
2019-07-26 13:06 ` Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 4/6] xentop: show CPU load information Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 5/6] arm64: сall enter_hypervisor_head only when it is needed Andrii Anisov
2019-07-26 10:44 ` Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 5/6] arm64: call " Andrii Anisov
2019-07-26 10:59 ` Julien Grall
2019-07-30 17:35 ` Andrii Anisov
2019-07-31 11:02 ` Julien Grall
2019-07-31 11:33 ` Andre Przywara
2019-08-01 7:33 ` Andrii Anisov
2019-08-01 10:17 ` Julien Grall
2019-08-02 13:50 ` Andrii Anisov
2019-07-26 10:37 ` [Xen-devel] [RFC 6/6] schedule: account all the hypervisor time to the idle vcpu Andrii Anisov
2019-07-26 11:56 ` [Xen-devel] [RFC 0/6] XEN scheduling hardening Dario Faggioli
2019-07-26 12:14 ` Juergen Gross
2019-07-29 11:53 ` Dario Faggioli
2019-07-29 12:13 ` Juergen Gross
2019-07-29 14:47 ` Andrii Anisov
2019-07-29 18:46 ` Dario Faggioli [this message]
2019-07-29 14:28 ` Andrii Anisov
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