From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id C51666B004D for ; Tue, 20 Dec 2011 16:58:19 -0500 (EST) Date: Tue, 20 Dec 2011 13:58:17 -0800 From: Andrew Morton Subject: Re: [PATCH 1/4] memcg: simplify page cache charging. Message-Id: <20111220135817.5ba7ab05.akpm@linux-foundation.org> In-Reply-To: <20111219090122.66024659.kamezawa.hiroyu@jp.fujitsu.com> References: <20111214164734.4d7d6d97.kamezawa.hiroyu@jp.fujitsu.com> <20111214164922.05fb4afe.kamezawa.hiroyu@jp.fujitsu.com> <20111216142814.dbb77209.akpm@linux-foundation.org> <20111219090122.66024659.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "hannes@cmpxchg.org" , Michal Hocko , Hugh Dickins , Ying Han On Mon, 19 Dec 2011 09:01:22 +0900 KAMEZAWA Hiroyuki wrote: > On Fri, 16 Dec 2011 14:28:14 -0800 > Andrew Morton wrote: > > > On Wed, 14 Dec 2011 16:49:22 +0900 > > KAMEZAWA Hiroyuki wrote: > > > > > Because of commit ef6a3c6311, FUSE uses replace_page_cache() instead > > > of add_to_page_cache(). Then, mem_cgroup_cache_charge() is not > > > called against FUSE's pages from splice. > > > > Speaking of ef6a3c6311 ("mm: add replace_page_cache_page() function"), > > may I pathetically remind people that it's rather inefficient? > > > > http://lkml.indiana.edu/hypermail/linux/kernel/1109.1/00375.html > > > > IIRC, people says inefficient because it uses memcg codes for page-migration > for fixing up accounting. Now, We added replace-page-cache for memcg in > memcg-add-mem_cgroup_replace_page_cache-to-fix-lru-issue.patch > > So, I think the problem originally mentioned is fixed. > No, the inefficiency in replace_page_cache_page() is still there. Two identical walks down the radix tree, a pointless decrement then increment of mapping->nrpages, two writes to page->mapping, an often pointless decrement then increment of NR_FILE_PAGES, and probably other things. -- 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