From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> To: Johannes Weiner <hannes@cmpxchg.org> Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>, "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>, "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>, "hugh.dickins@tiscali.co.uk" <hugh.dickins@tiscali.co.uk>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [RFC][PATCH 5/5] (experimental) chase and free cache only swap Date: Wed, 27 May 2009 10:31:07 +0900 [thread overview] Message-ID: <20090527103107.9c04eb55.kamezawa.hiroyu@jp.fujitsu.com> (raw) In-Reply-To: <20090527012658.GA9692@cmpxchg.org> On Wed, 27 May 2009 03:26:58 +0200 Johannes Weiner <hannes@cmpxchg.org> wrote: > On Wed, May 27, 2009 at 09:08:13AM +0900, KAMEZAWA Hiroyuki wrote: > > On Tue, 26 May 2009 20:14:00 +0200 > > Johannes Weiner <hannes@cmpxchg.org> wrote: > > > > > On Tue, May 26, 2009 at 12:18:34PM +0900, KAMEZAWA Hiroyuki wrote: > > > > > > > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > > > > > > > Just a trial/example patch. > > > > I'd like to consider more. Better implementation idea is welcome. > > > > > > > > When the system does swap-in/swap-out repeatedly, there are > > > > cache-only swaps in general. > > > > Typically, > > > > - swapped out in past but on memory now while vm_swap_full() returns true > > > > pages are cache-only swaps. (swap_map has no references.) > > > > > > > > This cache-only swaps can be an obstacles for smooth page reclaiming. > > > > Current implemantation is very naive, just scan & free. > > > > > > I think we can just remove that vm_swap_full() check in do_swap_page() > > > and try to remove the page from swap cache unconditionally. > > > > > I'm not sure why reclaim swap entry only at write fault. > > How do you come to that conclusion? Do you mean the current code does > that? yes. 2474 pte = mk_pte(page, vma->vm_page_prot); 2475 if (write_access && reuse_swap_page(page)) { 2476 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2477 write_access = 0; 2478 } > Did you understand that I suggested that? > I thought you suggested that swp_entry should be reclaimed in read-fault as same way as write-fault. Thanks, -Kame
WARNING: multiple messages have this Message-ID (diff)
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> To: Johannes Weiner <hannes@cmpxchg.org> Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>, "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>, "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>, "hugh.dickins@tiscali.co.uk" <hugh.dickins@tiscali.co.uk>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [RFC][PATCH 5/5] (experimental) chase and free cache only swap Date: Wed, 27 May 2009 10:31:07 +0900 [thread overview] Message-ID: <20090527103107.9c04eb55.kamezawa.hiroyu@jp.fujitsu.com> (raw) In-Reply-To: <20090527012658.GA9692@cmpxchg.org> On Wed, 27 May 2009 03:26:58 +0200 Johannes Weiner <hannes@cmpxchg.org> wrote: > On Wed, May 27, 2009 at 09:08:13AM +0900, KAMEZAWA Hiroyuki wrote: > > On Tue, 26 May 2009 20:14:00 +0200 > > Johannes Weiner <hannes@cmpxchg.org> wrote: > > > > > On Tue, May 26, 2009 at 12:18:34PM +0900, KAMEZAWA Hiroyuki wrote: > > > > > > > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > > > > > > > Just a trial/example patch. > > > > I'd like to consider more. Better implementation idea is welcome. > > > > > > > > When the system does swap-in/swap-out repeatedly, there are > > > > cache-only swaps in general. > > > > Typically, > > > > - swapped out in past but on memory now while vm_swap_full() returns true > > > > pages are cache-only swaps. (swap_map has no references.) > > > > > > > > This cache-only swaps can be an obstacles for smooth page reclaiming. > > > > Current implemantation is very naive, just scan & free. > > > > > > I think we can just remove that vm_swap_full() check in do_swap_page() > > > and try to remove the page from swap cache unconditionally. > > > > > I'm not sure why reclaim swap entry only at write fault. > > How do you come to that conclusion? Do you mean the current code does > that? yes. 2474 pte = mk_pte(page, vma->vm_page_prot); 2475 if (write_access && reuse_swap_page(page)) { 2476 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2477 write_access = 0; 2478 } > Did you understand that I suggested that? > I thought you suggested that swp_entry should be reclaimed in read-fault as same way as write-fault. Thanks, -Kame -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2009-05-27 1:32 UTC|newest] Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-05-26 3:12 [RFC][PATCH] memcg: fix swap account (26/May)[0/5] KAMEZAWA Hiroyuki 2009-05-26 3:12 ` KAMEZAWA Hiroyuki 2009-05-26 3:14 ` [RFC][PATCH 1/5] change swap cache interfaces KAMEZAWA Hiroyuki 2009-05-26 3:14 ` KAMEZAWA Hiroyuki 2009-05-26 3:15 ` [RFC][PATCH 2/5] add SWAP_HAS_CACHE flag to swap_map KAMEZAWA Hiroyuki 2009-05-26 3:15 ` KAMEZAWA Hiroyuki 2009-05-27 4:02 ` Daisuke Nishimura 2009-05-27 4:02 ` Daisuke Nishimura 2009-05-27 4:36 ` KAMEZAWA Hiroyuki 2009-05-27 4:36 ` KAMEZAWA Hiroyuki 2009-05-27 5:00 ` Daisuke Nishimura 2009-05-27 5:00 ` Daisuke Nishimura 2009-05-28 0:41 ` Daisuke Nishimura 2009-05-28 0:41 ` Daisuke Nishimura 2009-05-28 1:05 ` KAMEZAWA Hiroyuki 2009-05-28 1:05 ` KAMEZAWA Hiroyuki 2009-05-28 1:40 ` Daisuke Nishimura 2009-05-28 1:40 ` Daisuke Nishimura 2009-05-28 1:44 ` KAMEZAWA Hiroyuki 2009-05-28 1:44 ` KAMEZAWA Hiroyuki 2009-05-26 3:16 ` [RFC][PATCH 3/5] count cache-only swaps KAMEZAWA Hiroyuki 2009-05-26 3:16 ` KAMEZAWA Hiroyuki 2009-05-26 17:37 ` Johannes Weiner 2009-05-26 17:37 ` Johannes Weiner 2009-05-26 23:49 ` KAMEZAWA Hiroyuki 2009-05-26 23:49 ` KAMEZAWA Hiroyuki 2009-05-26 3:17 ` [RFC][PATCH 4/5] memcg: fix swap account KAMEZAWA Hiroyuki 2009-05-26 3:17 ` KAMEZAWA Hiroyuki 2009-05-26 3:18 ` [RFC][PATCH 5/5] (experimental) chase and free cache only swap KAMEZAWA Hiroyuki 2009-05-26 3:18 ` KAMEZAWA Hiroyuki 2009-05-26 18:14 ` Johannes Weiner 2009-05-26 18:14 ` Johannes Weiner 2009-05-27 0:08 ` KAMEZAWA Hiroyuki 2009-05-27 0:08 ` KAMEZAWA Hiroyuki 2009-05-27 1:26 ` Johannes Weiner 2009-05-27 1:26 ` Johannes Weiner 2009-05-27 1:31 ` KAMEZAWA Hiroyuki [this message] 2009-05-27 1:31 ` KAMEZAWA Hiroyuki 2009-05-27 2:06 ` Johannes Weiner 2009-05-27 2:06 ` Johannes Weiner 2009-05-27 5:14 ` KAMEZAWA Hiroyuki 2009-05-27 5:14 ` KAMEZAWA Hiroyuki 2009-05-27 6:30 ` Daisuke Nishimura 2009-05-27 6:30 ` Daisuke Nishimura 2009-05-27 6:50 ` KAMEZAWA Hiroyuki 2009-05-27 6:50 ` KAMEZAWA Hiroyuki 2009-05-27 6:43 ` [RFC][PATCH] memcg: fix swap account (26/May)[0/5] KAMEZAWA Hiroyuki 2009-05-27 6:43 ` KAMEZAWA Hiroyuki
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