From: Wanpeng Li <wanpeng.li@linux.intel.com>
To: Jason Low <jason.low2@hp.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>,
peterz@infradead.org, mingo@kernel.org, riel@redhat.com,
daniel.lezcano@linaro.org, vincent.guittot@linaro.org,
srikar@linux.vnet.ibm.com, pjt@google.com,
benh@kernel.crashing.org, efault@gmx.de,
linux-kernel@vger.kernel.org, iamjoonsoo.kim@lge.com,
svaidy@linux.vnet.ibm.com, tim.c.chen@linux.intel.com,
morten.rasmussen@arm.com, Wanpeng Li <wanpeng.li@linux.intel.com>
Subject: Re: [PATCH V2] sched: Improve load balancing in the presence of idle CPUs
Date: Fri, 27 Mar 2015 14:43:31 +0800 [thread overview]
Message-ID: <20150327064331.GA5419@kernel> (raw)
In-Reply-To: <1427432841.2788.10.camel@j-VirtualBox>
On Thu, Mar 26, 2015 at 10:07:21PM -0700, Jason Low wrote:
>On Fri, 2015-03-27 at 10:12 +0800, Wanpeng Li wrote:
>> Hi Preeti,
>> On Thu, Mar 26, 2015 at 06:32:44PM +0530, Preeti U Murthy wrote:
>> >
>> >1. An ILB CPU was chosen from the first numa domain to trigger nohz idle
>> >load balancing [Given the experiment, upto 6 CPUs per core could be
>> >potentially idle in this domain.]
>> >
>> >2. However the ILB CPU would call load_balance() on itself before
>> >initiating nohz idle load balancing.
>> >
>> >3. Given cores are SMT8, the ILB CPU had enough opportunities to pull
>> >tasks from its sibling cores to even out load.
>> >
>> >4. Now that the ILB CPU was no longer idle, it would abort nohz idle
>> >load balancing
>>
>> I don't see abort nohz idle load balancing when ILB CPU was no longer idle
>> in nohz_idle_balance(), could you explain more in details?
>
>Hi Wanpeng,
>
>In nohz_idle_balance(), there is a check for need_resched() so if the
>cpu has something to run, it should exit nohz_idle_balance(), which may
>cause it to not do the idle balancing on the other CPUs.
Got it, thanks. ;)
Regards,
Wanpeng Li
>
>
next prev parent reply other threads:[~2015-03-27 7:01 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-26 13:02 [PATCH V2] sched: Improve load balancing in the presence of idle CPUs Preeti U Murthy
2015-03-26 17:03 ` Jason Low
2015-03-27 2:12 ` Wanpeng Li
2015-03-27 4:33 ` Preeti U Murthy
2015-03-27 4:23 ` Wanpeng Li
2015-03-27 5:01 ` Jason Low
2015-03-27 5:07 ` Jason Low
2015-03-27 5:39 ` Srikar Dronamraju
2015-03-27 7:00 ` Wanpeng Li
2015-03-27 6:43 ` Wanpeng Li [this message]
2015-03-27 16:23 ` Preeti U Murthy
2015-03-27 11:43 ` [tip:sched/core] " tip-bot for Preeti U Murthy
2015-03-27 13:03 ` [PATCH V2] " Srikar Dronamraju
2015-03-27 14:38 ` Morten Rasmussen
2015-03-27 16:46 ` Preeti U Murthy
2015-03-27 17:56 ` Morten Rasmussen
2015-03-30 7:26 ` Preeti U Murthy
2015-03-30 11:30 ` Morten Rasmussen
2015-03-30 11:06 ` Peter Zijlstra
2015-03-30 12:03 ` Morten Rasmussen
2015-03-30 12:24 ` Peter Zijlstra
2015-03-30 12:54 ` Peter Zijlstra
2015-03-30 13:29 ` Vincent Guittot
2015-03-30 14:01 ` Peter Zijlstra
2015-03-30 15:27 ` Morten Rasmussen
2015-03-31 8:58 ` Preeti U Murthy
2015-03-31 17:30 ` Jason Low
2015-04-01 6:28 ` Preeti U Murthy
2015-04-01 13:03 ` Morten Rasmussen
2015-04-02 0:55 ` Jason Low
2015-04-02 3:22 ` Preeti U Murthy
2015-03-30 13:45 ` Vincent Guittot
2015-03-31 8:06 ` Preeti U Murthy
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=20150327064331.GA5419@kernel \
--to=wanpeng.li@linux.intel.com \
--cc=benh@kernel.crashing.org \
--cc=daniel.lezcano@linaro.org \
--cc=efault@gmx.de \
--cc=iamjoonsoo.kim@lge.com \
--cc=jason.low2@hp.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=morten.rasmussen@arm.com \
--cc=peterz@infradead.org \
--cc=pjt@google.com \
--cc=preeti@linux.vnet.ibm.com \
--cc=riel@redhat.com \
--cc=srikar@linux.vnet.ibm.com \
--cc=svaidy@linux.vnet.ibm.com \
--cc=tim.c.chen@linux.intel.com \
--cc=vincent.guittot@linaro.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).