Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765720AbYHDVtz (ORCPT ); Mon, 4 Aug 2008 17:49:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1770320AbYHDVjk (ORCPT ); Mon, 4 Aug 2008 17:39:40 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:56893 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1770238AbYHDVji (ORCPT ); Mon, 4 Aug 2008 17:39:38 -0400 Date: Tue, 5 Aug 2008 00:39:36 +0300 (EEST) From: Pekka J Enberg To: linux-kernel@vger.kernel.org, linux-mm@kvack.org cc: matthew@wil.cx, akpm@linux-foundation.org, cl@linux-foundation.org Subject: [RFC/PATCH] SLUB: dynamic per-cache MIN_PARTIAL Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4953 Lines: 152 From: Pekka Enberg This patch changes the static MIN_PARTIAL to a dynamic per-cache ->min_partial value that is calculated from object size. The bigger the object size, the more pages we keep on the partial list. I tested SLAB, SLUB, and SLUB with this patch on Jens Axboe's 'netio' example script of the fio benchmarking tool. The script stresses the networking subsystem which should also give a fairly good beating of kmalloc() et al. To run the test yourself, first clone the fio repository: git clone git://git.kernel.dk/fio.git and then run the following command n times on your machine: time ./fio examples/netio The results on my 2-way 64-bit x86 machine are as follows: [ the minimum, maximum, and average are captured from 50 individual runs ] real time (seconds) min max avg sd SLAB 22.76 23.38 22.98 0.17 SLUB 22.80 25.78 23.46 0.72 SLUB (dynamic) 22.74 23.54 23.00 0.20 sys time (seconds) min max avg sd SLAB 6.90 8.28 7.70 0.28 SLUB 7.42 16.95 8.89 2.28 SLUB (dynamic) 7.17 8.64 7.73 0.29 user time (seconds) min max avg sd SLAB 36.89 38.11 37.50 0.29 SLUB 30.85 37.99 37.06 1.67 SLUB (dynamic) 36.75 38.07 37.59 0.32 As you can see from the above numbers, this patch brings SLUB to the same level as SLAB for this particular workload fixing a ~2% regression. I'd expect this change to help similar workloads that allocate a lot of objects that are close to the size of a page. Cc: Matthew Wilcox Cc: Andrew Morton Cc: Christoph Lameter Signed-off-by: Pekka Enberg --- include/linux/slub_def.h | 1 + mm/slub.c | 26 +++++++++++++++++++------- 2 files changed, 20 insertions(+), 7 deletions(-) Index: slab-2.6/include/linux/slub_def.h =================================================================== --- slab-2.6.orig/include/linux/slub_def.h 2008-08-05 00:35:42.000000000 +0300 +++ slab-2.6/include/linux/slub_def.h 2008-08-05 00:36:21.000000000 +0300 @@ -46,6 +46,7 @@ struct kmem_cache_node { spinlock_t list_lock; /* Protect partial list and nr_partial */ unsigned long nr_partial; + unsigned long min_partial; struct list_head partial; #ifdef CONFIG_SLUB_DEBUG atomic_long_t nr_slabs; Index: slab-2.6/mm/slub.c =================================================================== --- slab-2.6.orig/mm/slub.c 2008-08-05 00:35:42.000000000 +0300 +++ slab-2.6/mm/slub.c 2008-08-05 00:36:27.000000000 +0300 @@ -1329,7 +1329,7 @@ n = get_node(s, zone_to_nid(zone)); if (n && cpuset_zone_allowed_hardwall(zone, flags) && - n->nr_partial > MIN_PARTIAL) { + n->nr_partial > n->min_partial) { page = get_partial_node(n); if (page) return page; @@ -1381,7 +1381,7 @@ slab_unlock(page); } else { stat(c, DEACTIVATE_EMPTY); - if (n->nr_partial < MIN_PARTIAL) { + if (n->nr_partial < n->min_partial) { /* * Adding an empty slab to the partial slabs in order * to avoid page allocator overhead. This slab needs @@ -1913,9 +1913,21 @@ #endif } -static void init_kmem_cache_node(struct kmem_cache_node *n) +static void +init_kmem_cache_node(struct kmem_cache_node *n, struct kmem_cache *s) { n->nr_partial = 0; + + /* + * The larger the object size is, the more pages we want on the partial + * list to avoid pounding the page allocator excessively. + */ + n->min_partial = ilog2(s->size); + if (n->min_partial < MIN_PARTIAL) + n->min_partial = MIN_PARTIAL; + else if (n->min_partial > MAX_PARTIAL) + n->min_partial = MAX_PARTIAL; + spin_lock_init(&n->list_lock); INIT_LIST_HEAD(&n->partial); #ifdef CONFIG_SLUB_DEBUG @@ -2087,7 +2099,7 @@ init_object(kmalloc_caches, n, 1); init_tracking(kmalloc_caches, n); #endif - init_kmem_cache_node(n); + init_kmem_cache_node(n, kmalloc_caches); inc_slabs_node(kmalloc_caches, node, page->objects); /* @@ -2144,7 +2156,7 @@ } s->node[node] = n; - init_kmem_cache_node(n); + init_kmem_cache_node(n, s); } return 1; } @@ -2155,7 +2167,7 @@ static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags) { - init_kmem_cache_node(&s->local_node); + init_kmem_cache_node(&s->local_node, s); return 1; } #endif @@ -2889,7 +2901,7 @@ ret = -ENOMEM; goto out; } - init_kmem_cache_node(n); + init_kmem_cache_node(n, s); s->node[nid] = n; } out: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/