From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from wpaz13.hot.corp.google.com (wpaz13.hot.corp.google.com [172.24.198.77]) by smtp-out.google.com with ESMTP id mB81hk91026222 for ; Sun, 7 Dec 2008 17:43:46 -0800 Received: from wf-out-1314.google.com (wfg24.prod.google.com [10.142.7.24]) by wpaz13.hot.corp.google.com with ESMTP id mB81hi2n029408 for ; Sun, 7 Dec 2008 17:43:45 -0800 Received: by wf-out-1314.google.com with SMTP id 24so1044789wfg.7 for ; Sun, 07 Dec 2008 17:43:44 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <493A4C1C.3020102@gmail.com> References: <604427e00812051140s67b2a89dm35806c3ee3b6ed7a@mail.gmail.com> <493A4B48.1050706@gmail.com> <493A4C1C.3020102@gmail.com> Date: Sun, 7 Dec 2008 17:43:44 -0800 Message-ID: <604427e00812071743u79e6d1d3y7ba510a7ff3052ec@mail.gmail.com> Subject: Re: [RFC v2][PATCH]page_fault retry with NOPAGE_RETRY From: Ying Han Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: owner-linux-mm@kvack.org Return-Path: To: =?ISO-8859-1?Q?T=F6r=F6k_Edwin?= Cc: linux-mm@kvack.org, linux-kernel , akpm , Ingo Molnar , Mike Waychison , David Rientjes , Rohit Seth , Hugh Dickins , Peter Zijlstra , "H. Peter Anvin" , Lee Schermerhorn , Nick Piggin List-ID: Thanks Torok for your experiment and that sounds great ! --Ying On Sat, Dec 6, 2008 at 1:55 AM, Torok Edwin wrote: > On 2008-12-06 11:52, Torok Edwin wrote: >> On 2008-12-05 21:40, Ying Han wrote: >> >>> changelog[v2]: >>> - reduce the runtime overhead by extending the 'write' flag of >>> handle_mm_fault() to indicate the retry hint. >>> - add another two branches in filemap_fault with retry logic. >>> - replace find_lock_page with find_lock_page_retry to make the code >>> cleaner. >>> >>> todo: >>> - there is potential a starvation hole with the retry. By the time the >>> retry returns, the pages might be released. we can make change by holding >>> page reference as well as remembering what the page "was"(in case the >>> file was truncated). any suggestion here are welcomed. >>> >>> I also made patches for all other arch. I am posting x86_64 here first and >>> i will post others by the time everyone feels comfortable of this patch. >>> >>> Edwin, please test this patch with your testcase and check if you get any >>> performance improvement of mmap over read. I added another two more places >>> in filemap_fault with retry logic which you might hit in your privous >>> experiment. >>> >>> >> >> I get much better results with this patch than with v1, thanks! >> >> mmap now scales almost as well as read does (there is a small ~5% >> overhead), which is a significant improvement over not scaling at all! >> >> Here are the results when running my testcase: >> >> Number of threads ->, 1,,, 2,,, 4,,, 8,,, 16 >> Kernel version, read, mmap, mixed, read, mmap, mixed, read, mmap, mixed, >> read, mmap, mixed, read, mmap, mixed >> 2.6.28-rc7-tip, 27.55, 26.18, 27.06, 16.18, 16.97, 16.10, 11.06, 11.64, >> 11.41, 9.38, 9.97, 9.31, 9.37, 9.82, 9.3 >> >> >> Here are the /proc/lock_stat output when running my testcase, contention >> is lower (34911+10462 vs 58590+7231), and waittime-total is better >> (57 601 464 vs 234 170 024) >> >> lock_stat version 0.3 >> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >> class name con-bounces contentions >> waittime-min waittime-max waittime-total acq-bounces >> acquisitions holdtime-min holdtime-max holdtime-total >> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >> &mm->mmap_sem-W: 5843 >> 10462 2.89 138824.72 14217159.52 >> 18965 84205 1.81 5031.07 725293.65 >> &mm->mmap_sem-R: 20208 >> 34911 4.87 136797.26 57601464.49 55797 >> 1110394 1.89 164918.52 30551371.71 >> --------------- >> &mm->mmap_sem 5341 >> [] sys_munmap+0x47/0x80 >> &mm->mmap_sem 28579 >> [] do_page_fault+0x172/0xab0 >> &mm->mmap_sem 5030 >> [] sys_mmap+0xf1/0x140 >> &mm->mmap_sem 6331 >> [] find_lock_page_retry+0xde/0xf0 >> --------------- >> &mm->mmap_sem 13558 >> [] find_lock_page_retry+0xde/0xf0 >> &mm->mmap_sem 4694 >> [] sys_munmap+0x47/0x80 >> &mm->mmap_sem 3681 >> [] sys_mmap+0xf1/0x140 >> &mm->mmap_sem 23374 >> [] do_page_fault+0x172/0xab0 >> >> >> On clamd: >> >> Here holdtime-total is better (1 493 154 + 2 395 987 vs 2 087 538 + 2 >> 514 673), and number of contentions on read >> (458 052 vs 5851 > > typo, should have been: 458 052 vs 585 119 > > -- 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