From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
kvm <kvm@vger.kernel.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>,
Wanpeng Li <wanpeng.li@hotmail.com>,
Ingo Molnar <mingo@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Rik van Riel <riel@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: Fw: [PATCH v4 2/3] sched/cputime: Fix prev steal time accouting during cpu hotplug
Date: Tue, 7 Jun 2016 13:53:26 +0200 [thread overview]
Message-ID: <0fd9638b-b0f7-156e-e314-bb32a4720773@redhat.com> (raw)
In-Reply-To: <CANRm+Cxgx7LaP6Jq23xhzM2BSxKkuLpO6pjmzS-uK+58xSV6vQ@mail.gmail.com>
On 07/06/2016 13:50, Wanpeng Li wrote:
>> > I'm not sure this patch is necessary. Instead you could just revert
>> > commit e9532e69b8d1. The previous patch obviously makes it unnecessary
>> > to reset rq->prev_steal_time and rq->prev_steal_time_rq, and the reset
>> > of rq->prev_irq_time looks like a no-op to me.
> The reason why I'm not just simple revert it is that commit mentioned
> "steal is smaller than rq->prev_steal_time we end up with an insane
> large value which then gets added to rq->prev_steal_time, resulting in
> a permanent wreckage of the accounting."
With this patch, you go back to having underflow if steal is smaller
than rq->prev_steal_time. The point is that it should never be smaller;
it was only smaller because of the bug that you are fixing in patch 1.
Thanks,
Paolo
Though I didn't meet such
> scenario. So I just do what that commit really want to do.
next prev parent reply other threads:[~2016-06-07 11:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1465661590-4732-1-git-send-email-wanpeng.li@hotmail.com>
[not found] ` <SG2PR02MB15507073C531BAA82E9C8E67805D0@SG2PR02MB1550.apcprd02.prod.outlook.com>
2016-06-07 10:34 ` [PATCH v4 2/3] sched/cputime: Fix prev steal time accouting during cpu hotplug Paolo Bonzini
[not found] ` <SG2PR02MB15505ACED7653E515DE21620805D0@SG2PR02MB1550.apcprd02.prod.outlook.com>
2016-06-07 11:50 ` Fw: " Wanpeng Li
2016-06-07 11:53 ` Paolo Bonzini [this message]
[not found] ` <SG2PR02MB15501BB06CAE47E4406FF7AD805D0@SG2PR02MB1550.apcprd02.prod.outlook.com>
2016-06-07 10:47 ` [PATCH v4 3/3] sched/cputime: Add steal time support to full dynticks CPU time accounting Paolo Bonzini
2016-06-07 11:23 ` Wanpeng Li
2016-06-07 12:15 ` Wanpeng Li
2016-06-07 12:34 ` Paolo Bonzini
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=0fd9638b-b0f7-156e-e314-bb32a4720773@redhat.com \
--to=pbonzini@redhat.com \
--cc=fweisbec@gmail.com \
--cc=kernellwp@gmail.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
--cc=wanpeng.li@hotmail.com \
/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).