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From: Ingo Molnar <mingo@kernel.org>
To: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	mingo@redhat.com, linux-kernel@vger.kernel.org,
	aarcange@redhat.com, Michel Lespinasse <walken@google.com>
Subject: Re: [PATCH 4/2] numa, mm: Rename the PROT_NONE fault handling functions
Date: Sun, 21 Oct 2012 15:43:41 +0200	[thread overview]
Message-ID: <20121021134341.GA23820@gmail.com> (raw)
In-Reply-To: <20121021132921.GA23425@gmail.com>


* Ingo Molnar <mingo@kernel.org> wrote:

> > Michel indicated that he does not use PROT_NONE for his 
> > working set estimation code, but instead checks the accessed 
> > bits in the page tables.
> 
> The pte_young() WSS method has a couple of fundamental 
> limitations:
> 
>  - it doesn't work with shared memory very well, the pte is per
>    mapping, not per page. The PROT_NONE method instruments the
>    physical page in essence.
> 
>  - it does not tell us which task touched the pte, in a
>    multi-threaded program
> 
> So like Peter I'd too expect these new WSS methods to eventually 
> be picked up for any serious WSS work.

Nevertheless lets wait and see until it actually happens - and 
meanwhile the prot_none namings are confusing.

So I've applied your patch as-is, with two more (new) usage 
sites converted as well. Will push it out after a bit of 
testing.

Thanks,

	Ingo

  reply	other threads:[~2012-10-21 13:43 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-18 21:18 [PATCH 0/2] minor NUMA cleanups & documentation Rik van Riel
2012-10-18 21:19 ` [PATCH 1/2] add credits for NUMA placement Rik van Riel
2012-10-19 11:41   ` Peter Zijlstra
2012-10-19 12:02   ` [tip:numa/core] numa: Add " tip-bot for Rik van Riel
2012-10-28 17:11   ` [tip:numa/core] sched, numa, mm: " tip-bot for Rik van Riel
2012-11-13 15:31   ` tip-bot for Rik van Riel
2012-11-13 17:23   ` tip-bot for Rik van Riel
2012-11-19 19:46   ` tip-bot for Rik van Riel
2012-10-18 21:20 ` [PATCH 2/2] rename NUMA fault handling functions Rik van Riel
2012-10-19 11:41   ` Peter Zijlstra
2012-10-19 14:07     ` Rik van Riel
2012-10-19 20:54       ` Ingo Molnar
2012-10-21 12:50         ` [PATCH 4/2] numa, mm: Rename the PROT_NONE " Ingo Molnar
2012-10-21 13:22           ` Rik van Riel
2012-10-21 13:29             ` Ingo Molnar
2012-10-21 13:43               ` Ingo Molnar [this message]
2012-10-20 10:15     ` [PATCH 2/2] rename NUMA " Michel Lespinasse
2012-10-21 15:20   ` [tip:numa/core] numa, mm: Rename the PROT_NONE fault handling functions to *_numa() tip-bot for Rik van Riel
2012-10-23 11:00   ` tip-bot for Rik van Riel
2012-10-21 12:43 ` [PATCH 3/2] sched, numa, mm: Implement constant rate working set sampling Ingo Molnar

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