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Re: [RFC][PATCH] page reclaim throttle take2

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To: Balbir Singh <balbir@...>
Cc: KOSAKI Motohiro <kosaki.motohiro@...>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...>, Peter Zijlstra <a.p.zijlstra@...>, <linux-kernel@...>, <linux-mm@...>, Rik van Riel <riel@...>, Lee Schermerhorn <Lee.Schermerhorn@...>, Nick Piggin <npiggin@...>
Date: Wednesday, February 27, 2008 - 2:09 am

On Wed, 27 Feb 2008, Balbir Singh wrote:


We lack node hotplug, so the dependence on the number of system nodes in 
the equation is static and can easily be defined at compile-time.

I agree that the maximum number of parallel reclaim threads should be a 
function of cpus, so you can easily make it that by adding callback 
functions for cpu hotplug events.

Perhaps a better alternative than creating a set of heuristics and setting 
a user-defined maximum on the number of concurrent reclaim threads is to 
configure the number of threads to be used for each online cpu called 
CONFIG_NUM_RECLAIM_THREADS_PER_CPU.  This solves the lock contention 
problem if configured properly that was mentioned earlier.

Adding yet another sysctl for this functionality seems unnecessary, unless 
it is attempting to address other VM problems where page reclaim needs to 
be throttled when it is being stressed.  Those issues need to be addressed 
directly, in my opinion, instead of attempting to workaround it by 
limiting the number of concurrent reclaim threads.

		David
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Messages in current thread:
[RFC][PATCH] page reclaim throttle take2 , KOSAKI Motohiro, (Mon Feb 25, 10:32 pm)
Re: [RFC][PATCH] page reclaim throttle take2, Peter Zijlstra, (Tue Feb 26, 5:18 pm)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 12:26 am)
Re: [RFC][PATCH] page reclaim throttle take2, Balbir Singh, (Wed Feb 27, 12:27 am)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 12:45 am)
Re: [RFC][PATCH] page reclaim throttle take2, KAMEZAWA Hiroyuki, (Wed Feb 27, 1:00 am)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 1:04 am)
Re: [RFC][PATCH] page reclaim throttle take2, Balbir Singh, (Wed Feb 27, 1:03 am)
Re: [RFC][PATCH] page reclaim throttle take2, David Rientjes, (Wed Feb 27, 1:19 am)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 1:33 am)
Re: [RFC][PATCH] page reclaim throttle take2, David Rientjes, (Wed Feb 27, 1:47 am)
Re: [RFC][PATCH] page reclaim throttle take2, Balbir Singh, (Wed Feb 27, 1:48 am)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 2:52 am)
Re: [RFC][PATCH] page reclaim throttle take2, David Rientjes, (Wed Feb 27, 2:09 am)
Re: [RFC][PATCH] page reclaim throttle take2, Balbir Singh, (Wed Feb 27, 3:59 am)
Re: [RFC][PATCH] page reclaim throttle take2, David Rientjes, (Wed Feb 27, 4:47 am)
Re: [RFC][PATCH] page reclaim throttle take2, Balbir Singh, (Wed Feb 27, 5:01 am)
Re: [RFC][PATCH] page reclaim throttle take2, Peter Zijlstra, (Wed Feb 27, 5:44 am)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 3:10 am)
Re: [RFC][PATCH] page reclaim throttle take2, David Rientjes, (Wed Feb 27, 3:19 am)
Re: [RFC][PATCH] page reclaim throttle take2, Rik van Riel, (Wed Feb 27, 11:30 am)
Re: [RFC][PATCH] page reclaim throttle take2, KAMEZAWA Hiroyuki, (Wed Feb 27, 3:51 am)
Re: [RFC][PATCH] page reclaim throttle take2, David Rientjes, (Wed Feb 27, 3:56 am)
Re: [RFC][PATCH] page reclaim throttle take2, KAMEZAWA Hiroyuki, (Wed Feb 27, 4:09 am)
Re: [RFC][PATCH] page reclaim throttle take2, KOSAKI Motohiro, (Wed Feb 27, 1:13 am)
Re: [RFC][PATCH] page reclaim throttle take2, KAMEZAWA Hiroyuki, (Tue Feb 26, 8:50 pm)
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