From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759323AbYF3Hsx (ORCPT ); Mon, 30 Jun 2008 03:48:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752649AbYF3Hso (ORCPT ); Mon, 30 Jun 2008 03:48:44 -0400 Received: from e28smtp06.in.ibm.com ([59.145.155.6]:44181 "EHLO e28esmtp06.in.ibm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753478AbYF3Hsn (ORCPT ); Mon, 30 Jun 2008 03:48:43 -0400 Message-ID: <48688FCB.9040205@linux.vnet.ibm.com> Date: Mon, 30 Jun 2008 13:18:27 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com Organization: IBM User-Agent: Thunderbird 2.0.0.14 (X11/20080505) MIME-Version: 1.0 To: KOSAKI Motohiro CC: Andrew Morton , YAMAMOTO Takashi , Paul Menage , linux-kernel@vger.kernel.org, linux-mm@kvack.org, KAMEZAWA Hiroyuki Subject: Re: [RFC 5/5] Memory controller soft limit reclaim on contention References: <20080627151808.31664.36047.sendpatchset@balbir-laptop> <20080627151906.31664.7247.sendpatchset@balbir-laptop> <20080630161657.37E3.KOSAKI.MOTOHIRO@jp.fujitsu.com> In-Reply-To: <20080630161657.37E3.KOSAKI.MOTOHIRO@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KOSAKI Motohiro wrote: > Hi > > this code survive stress testing? > > >> + while (count-- && >> + ((mem = heap_delete_max(&mem_cgroup_heap)) != NULL)) { >> + BUG_ON(!mem->on_heap); >> + spin_unlock_irqrestore(&mem_cgroup_heap_lock, flags); >> + nr_reclaimed += try_to_free_mem_cgroup_pages(mem, >> + gfp_mask); >> + cond_resched(); >> + spin_lock_irqsave(&mem_cgroup_heap_lock, flags); >> + mem->on_heap = 0; >> + /* >> + * What should be the basis of breaking out? >> + */ >> + if (nr_reclaimed) >> + goto done; > > doubtful shortcut. > we shouldn't assume we need only one page. > There's a comment on top -- what should be the basis of breaking out? It definitely needs refinement, the current solution seemed to be working, so I kept it. > > >> #endif /* _LINUX_MEMCONTROL_H */ >> diff -puN mm/vmscan.c~memory-controller-soft-limit-reclaim-on-contention mm/vmscan.c >> diff -puN mm/page_alloc.c~memory-controller-soft-limit-reclaim-on-contention mm/page_alloc.c >> --- linux-2.6.26-rc5/mm/page_alloc.c~memory-controller-soft-limit-reclaim-on-contention 2008-06-27 20:43:10.000000000 +0530 >> +++ linux-2.6.26-rc5-balbir/mm/page_alloc.c 2008-06-27 20:43:10.000000000 +0530 >> @@ -1669,7 +1669,14 @@ nofail_alloc: >> reclaim_state.reclaimed_slab = 0; >> p->reclaim_state = &reclaim_state; >> >> - did_some_progress = try_to_free_pages(zonelist, order, gfp_mask); >> + /* >> + * First try to reclaim from memory control groups that have >> + * exceeded their soft limit >> + */ >> + did_some_progress = mem_cgroup_reclaim_on_contention(gfp_mask); >> + if (!did_some_progress) >> + did_some_progress = try_to_free_pages(zonelist, order, >> + gfp_mask); > > try_to_free_mem_cgroup_pages() assume memcg need only one page. > but this code break it. > > if anyone need several continuous memory, mem_cgroup_reclaim_on_contention() reclaim > one or a very few page and return >0, then cause page allocation failure. > > shouldn't we extend try_to_free_mem_cgroup_pages() agruments? > > > in addition, if we don't assume try_to_free_mem_cgroup_pages() need one page, > we should implement lumpy reclaim to mem_cgroup_isolate_pages(). > otherwise, cpu wasting significant increase. The memory controller currently controls just *user* pages, which are all of order 1. Since pages are faulted in at different times, lumpy reclaim was not the highest priority for the memory controller. NOTE: the pages are duplicated on the per-zone LRU, so lumpy reclaim from there should work just fine. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL