From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 885016B021D for ; Tue, 13 Apr 2010 03:09:47 -0400 (EDT) Received: by pzk30 with SMTP id 30so116516pzk.12 for ; Tue, 13 Apr 2010 00:09:44 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20100413144037.f714fdeb.kamezawa.hiroyu@jp.fujitsu.com> References: <1270900173-10695-1-git-send-email-lliubbo@gmail.com> <20100412164335.GQ25756@csn.ul.ie> <20100413144037.f714fdeb.kamezawa.hiroyu@jp.fujitsu.com> Date: Tue, 13 Apr 2010 15:09:42 +0800 Message-ID: Subject: Re: [PATCH] code clean rename alloc_pages_exact_node() From: Bob Liu Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki , Mel Gorman Cc: Minchan Kim , akpm@linux-foundation.org, linux-mm@kvack.org, cl@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com, penberg@cs.helsinki.fi, lethal@linux-sh.org, a.p.zijlstra@chello.nl, nickpiggin@yahoo.com.au, dave@linux.vnet.ibm.com, lee.schermerhorn@hp.com, rientjes@google.com List-ID: On 4/13/10, KAMEZAWA Hiroyuki wrote: > On Tue, 13 Apr 2010 13:34:52 +0900 > > Minchan Kim wrote: > > > > On Tue, Apr 13, 2010 at 1:43 AM, Mel Gorman wrote: > > > On Sat, Apr 10, 2010 at 07:49:32PM +0800, Bob Liu wrote: > > >> Since alloc_pages_exact_node() is not for allocate page from > > >> exact node but just for removing check of node's valid, > > >> rename it to alloc_pages_from_valid_node(). Else will make > > >> people misunderstanding. > > >> > > > > > > I don't know about this change either but as I introduced the original > > > function name, I am biased. My reading of it is - allocate me pages and > > > I know exactly which node I need. I see how it it could be read as > > > "allocate me pages from exactly this node" but I don't feel the new > > > naming is that much clearer either. > > > > Tend to agree. > > Then, don't change function name but add some comment? > > > > /* > > * allow pages from fallback if page allocator can't find free page in your nid. > > * If you want to allocate page from exact node, please use > > __GFP_THISNODE flags with > > * gfp_mask. > > */ > > static inline struct page *alloc_pages_exact_node(.... > > > > I vote for this rather than renaming. > > There are two functions > allo_pages_node() > alloc_pages_exact_node(). > > Sane progmrammers tend to see implementation details if there are 2 > similar functions. > > If I name the function, > alloc_pages_node_verify_nid() ? > > I think /* This doesn't support nid=-1, automatic behavior. */ is necessary > as comment. > > OFF_TOPIC > > If you want renaming, I think we should define NID=-1 as > > #define ARBITRARY_NID (-1) or > #define CURRENT_NID (-1) or > #define AUTO_NID (-1) > > or some. Then, we'll have concensus of NID=-1 support. > (Maybe some amount of programmers don't know what NID=-1 means.) > > The function will be > alloc_pages_node_no_auto_nid() /* AUTO_NID is not supported by this */ > or > alloc_pages_node_veryfy_nid() > > Maybe patch will be bigger and may fail after discussion. But it seems > worth to try. > Hm..It's a bit bigger. Actually, what I want to do was in my original mail several days ago, the title is "mempolicy:add GFP_THISNODE when allocing new page" What I concern is *just* we shouldn't fallback to other nodes if the dest node haven't enough free pages during migrate_pages(). The detail is below: In funtion migrate_pages(), if the dest node have no enough free pages,it will fallback to other nodes. Add GFP_THISNODE to avoid this, the same as what funtion new_page_node() do in migrate.c. Signed-off-by: Bob Liu --- mm/mempolicy.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 08f40a2..fc5ddf5 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -842,7 +842,8 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist, static struct page *new_node_page(struct page *page, unsigned long node, int **x) { - return alloc_pages_exact_node(node, GFP_HIGHUSER_MOVABLE, 0); + return alloc_pages_exact_node(node, + GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0); } Thanks. -- Regards, --Bob -- 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