From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id B96096B003D for ; Wed, 11 Mar 2009 06:52:22 -0400 (EDT) Date: Wed, 11 Mar 2009 11:52:10 +0100 From: Ingo Molnar Subject: Re: [PATCH 1/2] mm: use list.h for vma list Message-ID: <20090311105210.GB2282@elte.hu> References: <8c5a844a0903110255q45b7cdf4u1453ce40d495ee2c@mail.gmail.com> <20090311104018.GA2376@x200.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090311104018.GA2376@x200.localdomain> Sender: owner-linux-mm@kvack.org To: Alexey Dobriyan Cc: Daniel Lowengrub , linux-mm@kvack.org, a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org List-ID: * Alexey Dobriyan wrote: > On Wed, Mar 11, 2009 at 11:55:48AM +0200, Daniel Lowengrub wrote: > > Use the linked list defined list.h for the list of vmas that's stored > > in the mm_struct structure. Wrapper functions "vma_next" and > > "vma_prev" are also implemented. Functions that operate on more than > > one vma are now given a list of vmas as input. > > > Signed-off-by: Daniel Lowengrub > > That's not how S-o-b line should look like. > > > --- linux-2.6.28.7.vanilla/arch/alpha/kernel/osf_sys.c > > +++ linux-2.6.28.7/arch/alpha/kernel/osf_sys.c > > @@ -1197,7 +1197,7 @@ > > if (!vma || addr + len <= vma->vm_start) > > return addr; > > addr = vma->vm_end; > > - vma = vma->vm_next; > > + vma = vma_next(vma); > > Well, this bloats both mm_struct and vm_area_struct. here's some hard numbers from an earlier submission: | I made a script that runs 'time ./mmap-perf' 100 times and | outputs the average. | | The output on the standard kernel was: | | real: 1.022600 | user: 0.135900 | system: 0.852600 | | The output after the patch was: | | real: 0.815400 | user: 0.113200 | system: 0.622200 Which is a 25% speedup in MM performance - which looks very significant. Note: i have not repeated the measurements, and it still looks a bit too good - i'd have expected if there's such a low hanging 25% fruit in the MM we'd have fixed it already. ( Daniel - please preserve such measurements in changelogs. ) Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org