From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 9032D6B007B for ; Mon, 2 Nov 2009 10:35:34 -0500 (EST) Date: Tue, 3 Nov 2009 00:35:30 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCHv2 2/5] vmscan: Kill hibernation specific reclaim logic and unify it In-Reply-To: <200911012238.13083.rjw@sisk.pl> References: <20091102000855.F404.A69D9226@jp.fujitsu.com> <200911012238.13083.rjw@sisk.pl> Message-Id: <20091103002506.8869.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: "Rafael J. Wysocki" Cc: kosaki.motohiro@jp.fujitsu.com, LKML , Rik van Riel , linux-mm , Andrew Morton List-ID: > > Then, This patch changed shrink_all_memory() to only the wrapper function of > > do_try_to_free_pages(). it bring good reviewability and debuggability, and solve > > above problems. > > > > side note: Reclaim logic unificication makes two good side effect. > > - Fix recursive reclaim bug on shrink_all_memory(). > > it did forgot to use PF_MEMALLOC. it mean the system be able to stuck into deadlock. > > - Now, shrink_all_memory() got lockdep awareness. it bring good debuggability. > > As I said previously, I don't really see a reason to keep shrink_all_memory(). > > Do you think that removing it will result in performance degradation? Hmm... Probably, I misunderstood your mention. I thought you suggested to kill all hibernation specific reclaim code. I did. It's no performance degression. (At least, I didn't observe) But, if you hope to kill shrink_all_memory() function itsef, the short answer is, it's impossible. Current VM reclaim code need some preparetion to caller, and there are existing in both alloc_pages_slowpath() and try_to_free_pages(). We can't omit its preparation. Please see following shrink_all_memory() code. it's pretty small. it only have few vmscan preparation. I don't think it is hard to maintainance. ===================================================== unsigned long shrink_all_memory(unsigned long nr_to_reclaim) { struct reclaim_state reclaim_state; struct scan_control sc = { .gfp_mask = GFP_HIGHUSER_MOVABLE, .may_swap = 1, .may_unmap = 1, .may_writepage = 1, .nr_to_reclaim = nr_to_reclaim, .hibernation_mode = 1, .swappiness = vm_swappiness, .order = 0, .isolate_pages = isolate_pages_global, }; struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); struct task_struct *p = current; unsigned long nr_reclaimed; p->flags |= PF_MEMALLOC; lockdep_set_current_reclaim_state(sc.gfp_mask); reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state; nr_reclaimed = do_try_to_free_pages(zonelist, &sc); p->reclaim_state = NULL; lockdep_clear_current_reclaim_state(); p->flags &= ~PF_MEMALLOC; return nr_reclaimed; } -- 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