From: Avi Kivity <avi@redhat.com>
To: Mike Galbraith <efault@gmx.de>
Cc: Rik van Riel <riel@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Chris Wright <chrisw@sous-sol.org>
Subject: Re: [RFC -v2 PATCH 2/3] sched: add yield_to function
Date: Fri, 17 Dec 2010 17:09:24 +0200 [thread overview]
Message-ID: <4D0B7D24.5060207@redhat.com> (raw)
In-Reply-To: <1292569018.7772.75.camel@marge.simson.net>
On 12/17/2010 08:56 AM, Mike Galbraith wrote:
> > Surely that makes it a reasonable idea to call yield, and
> > get one of the other tasks on the current CPU running for
> > a bit?
>
> There's nothing wrong with trying to give up the cpu. It's the concept
> of a cross cpu yield_to() that I find mighty strange.
What's so strange about it? From a high level there are N runnable
tasks contending for M cpus. If task X really needs task Y to run, what
does it matter if task Y last ran on the same cpu as task X or not?
Do I correctly read between the lines that CFS maintains complete
fairness only on a cpu, but not globally? I hope I'm wrong, but
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND
8648 avi 20 0 106m 1092 148 R 80.4 0.0 0:26.03 1 bash
8656 avi 20 0 106m 1080 136 R 47.3 0.0 0:14.73 0 bash
8652 avi 20 0 106m 1080 136 R 47.0 0.0 0:15.36 0 bash
doesn't look too good (three infinite loops in bash started at the
roughly same time)
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-12-17 15:09 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 3:44 [RFC -v2 PATCH 0/3] directed yield for Pause Loop Exiting Rik van Riel
2010-12-14 3:45 ` [RFC -v2 PATCH 1/3] kvm: keep track of which task is running a KVM vcpu Rik van Riel
2010-12-14 3:46 ` [RFC -v2 PATCH 2/3] sched: add yield_to function Rik van Riel
2010-12-14 6:08 ` Mike Galbraith
2010-12-14 10:24 ` Srivatsa Vaddagiri
2010-12-14 11:03 ` Mike Galbraith
2010-12-14 11:26 ` Srivatsa Vaddagiri
2010-12-14 12:47 ` Mike Galbraith
2010-12-16 19:49 ` Rik van Riel
2010-12-17 6:56 ` Mike Galbraith
2010-12-17 7:15 ` Mike Galbraith
2010-12-18 17:08 ` Avi Kivity
2010-12-18 19:13 ` Mike Galbraith
2010-12-19 6:08 ` Avi Kivity
2010-12-20 15:40 ` Rik van Riel
2010-12-20 16:04 ` Mike Galbraith
2010-12-28 5:54 ` Mike Galbraith
2010-12-28 6:08 ` Gene Heskett
2010-12-28 6:16 ` Mike Galbraith
2010-12-28 16:18 ` Gene Heskett
2010-12-28 22:34 ` Rik van Riel
2010-12-17 15:09 ` Avi Kivity [this message]
2010-12-17 19:51 ` Mike Galbraith
2010-12-18 17:02 ` Avi Kivity
2010-12-18 19:06 ` Mike Galbraith
2010-12-19 6:21 ` Avi Kivity
2010-12-19 10:05 ` Mike Galbraith
2010-12-19 9:19 ` Avi Kivity
2010-12-19 11:18 ` Mike Galbraith
2010-12-20 8:39 ` Mike Galbraith
2010-12-20 8:45 ` Avi Kivity
2010-12-20 8:55 ` Mike Galbraith
2010-12-20 9:03 ` Avi Kivity
2010-12-20 9:30 ` Mike Galbraith
2010-12-20 9:46 ` Avi Kivity
2010-12-20 10:33 ` Mike Galbraith
2010-12-20 10:39 ` Avi Kivity
2010-12-20 10:46 ` Mike Galbraith
2010-12-20 10:49 ` Avi Kivity
2010-12-20 10:49 ` Avi Kivity
2010-12-20 10:50 ` Mike Galbraith
2010-12-20 11:06 ` Avi Kivity
2010-12-20 11:06 ` Avi Kivity
2010-12-14 12:22 ` Peter Zijlstra
2010-12-18 14:50 ` Rik van Riel
2010-12-14 3:48 ` [RFC -v2 PATCH 3/3] kvm: use yield_to instead of sleep in kvm_vcpu_on_spin Rik van Riel
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=4D0B7D24.5060207@redhat.com \
--to=avi@redhat.com \
--cc=a.p.zijlstra@chello.nl \
--cc=chrisw@sous-sol.org \
--cc=efault@gmx.de \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=riel@redhat.com \
--cc=vatsa@linux.vnet.ibm.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.