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 ESMTP id 2E4316B0012 for ; Tue, 7 Jun 2011 08:42:30 -0400 (EDT) Date: Tue, 7 Jun 2011 08:42:13 -0400 From: Christoph Hellwig Subject: Re: [patch 8/8] mm: make per-memcg lru lists exclusive Message-ID: <20110607124213.GB18571@infradead.org> References: <1306909519-7286-1-git-send-email-hannes@cmpxchg.org> <1306909519-7286-9-git-send-email-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1306909519-7286-9-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Ying Han , Michal Hocko , Andrew Morton , Rik van Riel , Minchan Kim , KOSAKI Motohiro , Mel Gorman , Greg Thelen , Michel Lespinasse , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Jun 01, 2011 at 08:25:19AM +0200, Johannes Weiner wrote: > All lru list walkers have been converted to operate on per-memcg > lists, the global per-zone lists are no longer required. > > This patch makes the per-memcg lists exclusive and removes the global > lists from memcg-enabled kernels. > > The per-memcg lists now string up page descriptors directly, which > unifies/simplifies the list isolation code of page reclaim as well as > it saves a full double-linked list head for each page in the system. > > At the core of this change is the introduction of the lruvec > structure, an array of all lru list heads. It exists for each zone > globally, and for each zone per memcg. All lru list operations are > now done in generic code against lruvecs, with the memcg lru list > primitives only doing accounting and returning the proper lruvec for > the currently scanned memcg on isolation, or for the respective page > on putback. Wouldn't it be simpler if we always have a stub mem_cgroup_per_zone structure even for non-memcg kernels, and always operate on a single instance per node of those for non-memcg kernels? In effect the lruvec almost is something like that, just adding another layer of abstraction. > static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) > diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h > index 8f7d247..43d5d9f 100644 > --- a/include/linux/mm_inline.h > +++ b/include/linux/mm_inline.h > @@ -25,23 +25,27 @@ static inline void > __add_page_to_lru_list(struct zone *zone, struct page *page, enum lru_list l, > struct list_head *head) > { > + /* NOTE: Caller must ensure @head is on the right lruvec! */ > + mem_cgroup_lru_add_list(zone, page, l); > list_add(&page->lru, head); > > __mod_zone_page_state(zone, NR_LRU_BASE + l, hpage_nr_pages(page)); > - mem_cgroup_add_lru_list(page, l); > } This already has been a borderline-useful function before, but with the new changes it's not a useful helper. Either add the code surrounding it includeing the PageLRU check and the normal add_page_to_lru_list into a new page_update_lru_pos or similar helper, or just opencode these bits in the only caller with a comment documenting why we are doing it. I would tend towards the opencoding variant. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org