From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: peterz@infradead.org, mingo@kernel.org, riel@redhat.com,
daniel.lezcano@linaro.org, vincent.guittot@linaro.org,
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, jason.low2@hp.com
Subject: Re: [PATCH V2] sched: Improve load balancing in the presence of idle CPUs
Date: Fri, 27 Mar 2015 18:33:55 +0530 [thread overview]
Message-ID: <20150327130355.GD6895@linux.vnet.ibm.com> (raw)
In-Reply-To: <20150326130014.21532.17158.stgit@preeti.in.ibm.com>
> When a CPU is kicked to do nohz idle balancing, it wakes up to do load
> balancing on itself, followed by load balancing on behalf of idle CPUs.
> But it may end up with load after the load balancing attempt on itself.
> This aborts nohz idle balancing. As a result several idle CPUs are left
> without tasks till such a time that an ILB CPU finds it unfavorable to
> pull tasks upon itself. This delays spreading of load across idle CPUs
> and worse, clutters only a few CPUs with tasks.
>
[..... snipped .... ]
> Fix this, by checking if a CPU was woken up to do nohz idle load
> balancing, before it does load balancing upon itself. This way we allow
> idle CPUs across the system to do load balancing which results in
> quicker spread of load, instead of performing load balancing within the
> local sched domain hierarchy of the ILB CPU alone under circumstances
> such as above.
>
> Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
> ---
Looks good to me.
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
next prev parent reply other threads:[~2015-03-27 13:04 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
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 ` Srikar Dronamraju [this message]
2015-03-27 14:38 ` [PATCH V2] " 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
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