From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 14 Mar 2008 11:16:09 +0000 (GMT) From: Hugh Dickins Subject: Re: [PATCH] Move memory controller allocations to their own slabs (v3) In-Reply-To: <20080314115645.e78b7f5c.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20080313140307.20133.30405.sendpatchset@localhost.localdomain> <20080314115645.e78b7f5c.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Balbir Singh , Andrew Morton , Pavel Emelianov , Sudhir Kumar , YAMAMOTO Takashi , Paul Menage , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, linux-mm@kvack.org, David Rientjes List-ID: On Fri, 14 Mar 2008, KAMEZAWA Hiroyuki wrote: > At first, in my understanding, > - MOVABLE is for migratable pages. (so, not for kernel objects.) > - RECLAIMABLE is for reclaimable kernel objects. (for slab etc..) > > All reclaimable objects are not necessary to be always reclaimable but > some amount of RECLAIMABLE objects (not all) should be recraimable easily. > For example, some of dentry-cache, inode-cache is reclaimable because *unused* > objects are cached. > > When it comes to page_cgroup, *all* objects has dependency to pages which are > assigned to. And user pages are reclaimable. > There is a similar object....the radix tree. radix-tree's node is allocated as > RECLAIMABLE object. > > So I think it makes sense to changing page_cgroup to be reclaimable. > > But final decision should be done by how fragmentation avoidance works. > It's good to test "how many hugepages can be allocated dynamically" when we > make page_cgroup to be GFP_RECAIMABLE I agree with you on all points. No need for it to be done in the same patch as Balbir's, but yes, __GFP_RECLAIMABLE appears to be appropriate for the page_cgroup kmem_cache. (I think it's a better fit than for the radix_tree_node cache: though the common pagecache usage of the radix_tree implies that its nodes are reclaimable, I can't see why radix_tree nodes would intrinsically be reclaimable. If a significant non-reclaimable user of radix-tree comes on the scene, I'd expect us to change that assumption.) Hugh -- 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