From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f44.google.com (mail-wg0-f44.google.com [74.125.82.44]) by kanga.kvack.org (Postfix) with ESMTP id 1F6FE6B0039 for ; Wed, 22 Jan 2014 13:49:16 -0500 (EST) Received: by mail-wg0-f44.google.com with SMTP id l18so679446wgh.35 for ; Wed, 22 Jan 2014 10:49:15 -0800 (PST) Received: from zene.cmpxchg.org (zene.cmpxchg.org. [2a01:238:4224:fa00:ca1f:9ef3:caee:a2bd]) by mx.google.com with ESMTPS id be10si7374803wjc.54.2014.01.22.10.49.14 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 22 Jan 2014 10:49:15 -0800 (PST) Date: Wed, 22 Jan 2014 13:48:36 -0500 From: Johannes Weiner Subject: Re: [patch 9/9] mm: keep page cache radix tree nodes in check Message-ID: <20140122184836.GE4407@cmpxchg.org> References: <1389377443-11755-1-git-send-email-hannes@cmpxchg.org> <1389377443-11755-10-git-send-email-hannes@cmpxchg.org> <20140117000517.GB18112@dastard> <20140120231737.GS6963@cmpxchg.org> <20140121030358.GN18112@dastard> <20140121055017.GT6963@cmpxchg.org> <20140122030607.GB27606@dastard> <20140122065714.GU6963@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140122065714.GU6963@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: Andrew Morton , Andi Kleen , Andrea Arcangeli , Bob Liu , Christoph Hellwig , Greg Thelen , Hugh Dickins , Jan Kara , KOSAKI Motohiro , Luigi Semenzato , Mel Gorman , Metin Doslu , Michel Lespinasse , Minchan Kim , Ozgun Erdogan , Peter Zijlstra , Rik van Riel , Roman Gushchin , Ryan Mallon , Tejun Heo , Vlastimil Babka , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, Jan 22, 2014 at 01:57:14AM -0500, Johannes Weiner wrote: > Not at this time, I'll try to look into that. For now, I am updating > the patch to revert the shrinker back to DEFAULT_SEEKS and change the > object count to only include objects above a certain threshold, which > assumes a worst-case population of 4 in 64 slots. It's not perfect, > but neither was the seeks magic, and it's easier to reason about what > it's actually doing. Ah, the quality of 2am submissions... 8 out of 64 of course. > @@ -266,14 +269,38 @@ struct list_lru workingset_shadow_nodes; > static unsigned long count_shadow_nodes(struct shrinker *shrinker, > struct shrink_control *sc) > { > - return list_lru_count_node(&workingset_shadow_nodes, sc->nid); > + unsigned long shadow_nodes; > + unsigned long max_nodes; > + unsigned long pages; > + > + shadow_nodes = list_lru_count_node(&workingset_shadow_nodes, sc->nid); > + pages = node_present_pages(sc->nid); > + /* > + * Active cache pages are limited to 50% of memory, and shadow > + * entries that represent a refault distance bigger than that > + * do not have any effect. Limit the number of shadow nodes > + * such that shadow entries do not exceed the number of active > + * cache pages, assuming a worst-case node population density > + * of 1/16th on average. 1/8th. The actual code is consistent: > + * On 64-bit with 7 radix_tree_nodes per page and 64 slots > + * each, this will reclaim shadow entries when they consume > + * ~2% of available memory: > + * > + * PAGE_SIZE / radix_tree_nodes / node_entries / PAGE_SIZE > + */ > + max_nodes = pages >> (1 + RADIX_TREE_MAP_SHIFT - 3); > + > + if (shadow_nodes <= max_nodes) > + return 0; > + > + return shadow_nodes - max_nodes; > } > > static enum lru_status shadow_lru_isolate(struct list_head *item, > spinlock_t *lru_lock, > void *arg) > { > - unsigned long *nr_reclaimed = arg; > struct address_space *mapping; > struct radix_tree_node *node; > unsigned int i; -- 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