Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752161Ab0LAGky (ORCPT ); Wed, 1 Dec 2010 01:40:54 -0500 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:59106 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751202Ab0LAGkx (ORCPT ); Wed, 1 Dec 2010 01:40:53 -0500 Date: Wed, 1 Dec 2010 12:10:43 +0530 From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, Christoph Lameter , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, kvm Subject: Re: [PATCH 3/3] Provide control over unmapped pages Message-ID: <20101201064043.GO2746@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20101130101126.17475.18729.stgit@localhost6.localdomain6> <20101130101602.17475.32611.stgit@localhost6.localdomain6> <20101201103254.b823eae0.kamezawa.hiroyu@jp.fujitsu.com> <20101201051816.GI2746@balbir.in.ibm.com> <20101201052259.GN2746@balbir.in.ibm.com> <20101201143550.0b652916.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20101201143550.0b652916.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3646 Lines: 86 * KAMEZAWA Hiroyuki [2010-12-01 14:35:50]: > On Wed, 1 Dec 2010 10:52:59 +0530 > Balbir Singh wrote: > > > * Balbir Singh [2010-12-01 10:48:16]: > > > > > * KAMEZAWA Hiroyuki [2010-12-01 10:32:54]: > > > > > > > On Tue, 30 Nov 2010 15:46:31 +0530 > > > > Balbir Singh wrote: > > > > > > > > > Provide control using zone_reclaim() and a boot parameter. The > > > > > code reuses functionality from zone_reclaim() to isolate unmapped > > > > > pages and reclaim them as a priority, ahead of other mapped pages. > > > > > > > > > > Signed-off-by: Balbir Singh > > > > > --- > > > > > include/linux/swap.h | 5 ++- > > > > > mm/page_alloc.c | 7 +++-- > > > > > mm/vmscan.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++- > > > > > 3 files changed, 79 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/include/linux/swap.h b/include/linux/swap.h > > > > > index eba53e7..78b0830 100644 > > > > > --- a/include/linux/swap.h > > > > > +++ b/include/linux/swap.h > > > > > @@ -252,11 +252,12 @@ extern int vm_swappiness; > > > > > extern int remove_mapping(struct address_space *mapping, struct page *page); > > > > > extern long vm_total_pages; > > > > > > > > > > -#ifdef CONFIG_NUMA > > > > > -extern int zone_reclaim_mode; > > > > > extern int sysctl_min_unmapped_ratio; > > > > > extern int sysctl_min_slab_ratio; > > > > > extern int zone_reclaim(struct zone *, gfp_t, unsigned int); > > > > > +extern bool should_balance_unmapped_pages(struct zone *zone); > > > > > +#ifdef CONFIG_NUMA > > > > > +extern int zone_reclaim_mode; > > > > > #else > > > > > #define zone_reclaim_mode 0 > > > > > static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order) > > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > > > index 62b7280..4228da3 100644 > > > > > --- a/mm/page_alloc.c > > > > > +++ b/mm/page_alloc.c > > > > > @@ -1662,6 +1662,9 @@ zonelist_scan: > > > > > unsigned long mark; > > > > > int ret; > > > > > > > > > > + if (should_balance_unmapped_pages(zone)) > > > > > + wakeup_kswapd(zone, order); > > > > > + > > > > > > > > Hm, I'm not sure the final vision of this feature. Does this reclaiming feature > > > > can't be called directly via balloon driver just before alloc_page() ? > > > > > > > > > > That is a separate patch, this is a boot paramter based control > > > approach. > > > > > > > Do you need to keep page caches small even when there are free memory on host ? > > > > > > > > > > The goal is to avoid duplication, as you know page cache fills itself > > > to consume as much memory as possible. The host generally does not > > > have a lot of free memory in a consolidated environment. > > > > > That's a point. Then, why the guest has to do _extra_ work for host even when > the host says nothing ? I think trigger this by guests themselves is not very good. I've mentioned it before, the guest keeping free memory without a large performance hit, helps, the balloon driver is able to quickly retrieve this memory if required or the guest can use this memory for some other application/task. The cached data is mostly already present in the host page cache. -- Three Cheers, Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/