linux-kernel - Re: [PATCH 05/14] vrange: Add new vrange(2) system call

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Date:	Tue, 08 Oct 2013 00:35:33 -0400
From:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
To:	Minchan Kim <minchan@...nel.org>
CC:	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	John Stultz <john.stultz@...aro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Android Kernel Team <kernel-team@...roid.com>,
	Robert Love <rlove@...gle.com>, Mel Gorman <mel@....ul.ie>,
	Hugh Dickins <hughd@...gle.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Rik van Riel <riel@...hat.com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Dave Chinner <david@...morbit.com>, Neil Brown <neilb@...e.de>,
	Andrea Righi <andrea@...terlinux.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Mike Hommey <mh@...ndium.org>, Taras Glek <tglek@...illa.com>,
	Dhaval Giani <dhaval.giani@...il.com>, Jan Kara <jack@...e.cz>,
	Michel Lespinasse <walken@...gle.com>,
	Rob Clark <robdclark@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 05/14] vrange: Add new vrange(2) system call

(10/7/13 11:07 PM), Minchan Kim wrote:
> Hi KOSAKI,
>
> On Mon, Oct 07, 2013 at 10:51:18PM -0400, KOSAKI Motohiro wrote:
>>> Maybe, int madvise5(addr, length, MADV_DONTNEED|MADV_LAZY|MADV_SIGBUS,
>>>          &purged, &ret);
>>>
>>> Another reason to make it hard is that madvise(2) is tight coupled with
>>> with vmas split/merge. It needs mmap_sem's write-side lock and it hurt
>>> anon-vrange test performance much heavily and userland might want to
>>> make volatile range with small unit like "page size" so it's undesireable
>>> to make it with vma. Then, we should filter out to avoid vma split/merge
>>> in implementation if only MADV_LAZY case? Doable but it could make code
>>> complicated and lost consistency with other variant of madvise.
>>
>> I haven't seen your performance test result. Could please point out URLs?
>
> https://lkml.org/lkml/2013/3/12/105

It's not comparison with and without vma merge. I'm interest how much benefit
vmas operation avoiding have.

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