linux-kernel - Re: [PATCH 0/2] hugepage: optimize page fault path locking

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Message-ID: <20130729061820.GA4784@lge.com>
Date:	Mon, 29 Jul 2013 15:18:20 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Davidlohr Bueso <davidlohr.bueso@...com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Michel Lespinasse <walken@...gle.com>,
	Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...e.cz>,
	"AneeshKumarK.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hillf Danton <dhillf@...il.com>,
	Hugh Dickins <hughd@...gle.com>,
	David Gibson <david@...son.dropbear.id.au>,
	Eric B Munson <emunson@...bm.net>,
	Anton Blanchard <anton@...ba.org>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] hugepage: optimize page fault path locking

On Fri, Jul 26, 2013 at 07:27:23AM -0700, Davidlohr Bueso wrote:
> This patchset attempts to reduce the amount of contention we impose
> on the hugetlb_instantiation_mutex by replacing the global mutex with
> a table of mutexes, selected based on a hash. The original discussion can 
> be found here: http://lkml.org/lkml/2013/7/12/428

Hello, Davidlohr.

I recently sent a patchset which remove the hugetlb_instantiation_mutex
entirely ('mm, hugetlb: remove a hugetlb_instantiation_mutex').
This patchset can be found here: https://lkml.org/lkml/2013/7/29/54

If possible, could you review it and test it whether your problem is
disappered with it or not?

Thanks.

> 
> Patch 1: Allows the file region tracking list to be serialized by its own rwsem.
> This is necessary because the next patch allows concurrent hugepage fault paths,
> getting rid of the hugetlb_instantiation_mutex - which protects chains of struct 
> file_regionin inode->i_mapping->private_list (VM_MAYSHARE) or vma_resv_map(vma)->regions 
> (!VM_MAYSHARE).
> 
> Patch 2: From David Gibson, for some reason never made it into the kernel. 
> Further cleanups and enhancements from Anton Blanchard and myself.
> Details of how the hash key is selected is in the patch.
> 
> Davidlohr Bueso (2):
>   hugepage: protect file regions with rwsem
>   hugepage: allow parallelization of the hugepage fault path
> 
>  mm/hugetlb.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 106 insertions(+), 28 deletions(-)
> 
> -- 
> 1.7.11.7
> 
> --
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