From: Andrii Anisov <andrii.anisov@gmail.com>
To: Julien Grall <julien.grall@arm.com>,
Dario Faggioli <dfaggioli@suse.com>,
xen-devel@lists.xenproject.org
Cc: Andrii Anisov <andrii_anisov@epam.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [Xen-devel] [RFC 1/6] xen/arm: Re-enable interrupt later in the trap path
Date: Fri, 2 Aug 2019 16:07:49 +0300 [thread overview]
Message-ID: <d92cecb0-397a-004f-aa80-e2761d9fadb5@gmail.com> (raw)
In-Reply-To: <189da8d7-dee8-18f8-fbbf-699761f0b656@arm.com>
On 02.08.19 12:15, Julien Grall wrote:
>> I can make such a list, how it is done in this series:
>
> From the list below it is not clear what is the split between hypervisor time and guest time. See some of the examples below.
I guess your question is *why* do I split hyp/guest time in such a way.
So for the guest I count time spent in the guest mode. Plus time spent in hypervisor mode to serve explicit requests by guest.
That time may be quite deterministic from the guest's point of view.
But the time spent by hypervisor to handle interrupts, update the hardware state is not requested by the guest itself. It is a virtualization overhead. And the overhead heavily depends on the system configuration (e.g. how many guests are running).
That overhead may be accounted for a guest or for hyp, depending on the model agreed.
My idea is as following:
Accounting that overhead for guests is quite OK for server applications, you put server overhead time on guests and charge money from their budget.
Yet for RT applications you will have more accurate view on the guest execution time if you drop that overhead.
Our target is XEN in safety critical systems. So I chosen more deterministic (from my point of view) approach.
Well, I suppose we may add granularity to the time accounting, and then decide at the scheduler level what we count for the guest execution time.
But it is so far from the end, and we are here to discuss and agree the stuff.
--
Sincerely,
Andrii Anisov.
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next prev parent reply other threads:[~2019-08-02 13:08 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 [this message]
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
2019-07-29 14:28 ` Andrii Anisov
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