From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx186.postini.com [74.125.245.186]) by kanga.kvack.org (Postfix) with SMTP id 3054E6B005C for ; Mon, 4 Jun 2012 00:21:40 -0400 (EDT) Received: by qafl39 with SMTP id l39so1651393qaf.9 for ; Sun, 03 Jun 2012 21:21:39 -0700 (PDT) Message-ID: <4FCC37CE.3080203@gmail.com> Date: Mon, 04 Jun 2012 00:21:34 -0400 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: WARNING: at mm/page-writeback.c:1990 __set_page_dirty_nobuffers+0x13a/0x170() References: <20120530163317.GA13189@redhat.com> <20120531005739.GA4532@redhat.com> <20120601023107.GA19445@redhat.com> <20120601161205.GA1918@redhat.com> <20120601171606.GA3794@redhat.com> <4FCC0B09.1070708@kernel.org> <4FCC1D68.8060406@kernel.org> In-Reply-To: <4FCC1D68.8060406@kernel.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Hugh Dickins , Linus Torvalds , Bartlomiej Zolnierkiewicz , Kyungmin Park , Marek Szyprowski , Mel Gorman , Rik van Riel , Dave Jones , Andrew Morton , Cong Wang , Markus Trippelsdorf , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kosaki.motohiro@gmail.com > In changelog, Bartlomiej said. > > My particular test case (on a ARM EXYNOS4 device with 512 MiB, which means > 131072 standard 4KiB pages in 'Normal' zone) is to: > > - allocate 120000 pages for kernel's usage > - free every second page (60000 pages) of memory just allocated > - allocate and use 60000 pages from user space > - free remaining 60000 pages of kernel memory > (now we have fragmented memory occupied mostly by user space pages) > - try to allocate 100 order-9 (2048 KiB) pages for kernel's usage > > The results: > - with compaction disabled I get 11 successful allocations > - with compaction enabled - 14 successful allocations > - with this patch I'm able to get all 100 successful allocations > > I think above workload is really really artificial and theoretical so I didn't like > this patch but Mel seem to like it. :( > > Quote from Mel > " Ok, that is indeed an adverse workload that the current system will not > properly deal with. I think you are right to try fixing this but may need > a different approach that takes the cost out of the allocation/free path > and moves it the compaction path." > > We can correct this patch to work but at least need justification about it. > Do we really need this patch for such artificial workload? > what do you think? I'm ok to resubmit. But please change the thread. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org