linux-kernel - Re: [PATCH v4 1/5] nohz_full: add support for "cpu

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Date:	Fri, 24 Jul 2015 16:21:43 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Christoph Lameter <cl@...ux.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
CC:	Andy Lutomirski <luto@...capital.net>,
	Gilad Ben Yossef <giladb@...hip.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Tejun Heo <tj@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Linux API <linux-api@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/5] nohz_full: add support for "cpu_isolated" mode

On 07/22/2015 04:02 PM, Christoph Lameter wrote:
> On Wed, 22 Jul 2015, Paul E. McKenney wrote:
>
>>>> Didn't Christoph Lameter fix this?  Or is this an additional problem?
>>> Well the vmstat update must realize first that there are no outstanding
>>> updates before switching itself off. So typically there is one extra tick.
>>> But we could add another function that will simply fold the differential
>>> immediately and turn the kworker task in the expectation that the
>>> processor will stay quiet.
>> Got it, thank you!
>>
>> 								Thanx, Paul
> Ok here is a function that quiets down the vmstat kworkers.

That's great - I will include this patch in my series then, and call it
as part of the "hard isolation" mode return to userspace.  Thanks!

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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