From: Andrii Anisov <andrii.anisov@gmail.com>
To: Juergen Gross <jgross@suse.com>,
Dario Faggioli <dfaggioli@suse.com>,
xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Andrii Anisov <andrii_anisov@epam.com>,
George Dunlap <george.dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tim Deegan <tim@xen.org>, Julien Grall <julien.grall@arm.com>,
Jan Beulich <jbeulich@suse.com>
Subject: Re: [Xen-devel] [RFC 0/6] XEN scheduling hardening
Date: Mon, 29 Jul 2019 17:47:25 +0300 [thread overview]
Message-ID: <30bb656e-fe48-e92e-403c-efc8fb7e8cb7@gmail.com> (raw)
In-Reply-To: <25dfa166-c7a4-c2dd-0c1d-58faf5ffc296@suse.com>
Hello Juergen,
On 26.07.19 15:14, Juergen Gross wrote:
>>> - How to avoid the absolute top priority of tasklets (what is obeyed
>>> by all
>>> schedulers so far). Should idle vcpu be scheduled as the normal
>>> guest vcpus
>>> (through queues, priorities, etc)?
>>>
>> Now, this is something to think about, and try to understand if
>> anything would break if we go for it. I mean, I see why you'd want to
>> do that, but tasklets and softirqs works the way they do, in Xen, since
>> when they were introduced, I believe.
>>
>> Therefore, even if there wouldn't be any subsystem explicitly relying
>> on the current behavior (which should be verified), I think we are at
>> high risk of breaking things, if we change.
>
> We'd break things IMO.
>
> Tasklets are sometimes used to perform async actions which can't be done
> in guest vcpu context.
OK, that stuff can not be done in the guest vcpu context. But why can't it be done with the guest's priority?
> 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.
> 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?
--
Sincerely,
Andrii Anisov.
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-07-29 14:47 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 [this message]
2019-07-29 18:46 ` Dario Faggioli
2019-07-29 14:28 ` Andrii Anisov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=30bb656e-fe48-e92e-403c-efc8fb7e8cb7@gmail.com \
--to=andrii.anisov@gmail.com \
--cc=andrew.cooper3@citrix.com \
--cc=andrii_anisov@epam.com \
--cc=dfaggioli@suse.com \
--cc=george.dunlap@eu.citrix.com \
--cc=jbeulich@suse.com \
--cc=jgross@suse.com \
--cc=julien.grall@arm.com \
--cc=sstabellini@kernel.org \
--cc=tim@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).