From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Date: Thu, 14 Oct 2004 16:50:43 +0000 Subject: [PATCH] General purpose zeroed page slab Message-Id: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, akpm@osdl.org, tony.luck@intel.com A while back Bill Irwin converted the page table code on ppc64 to use a zeroed page slab. I recently did the same on ia64 and got a significant performance improvement in terms of fault time (4 usec -> 700 nsec). This cache needs to be initialized fairly early on and so far we've called it from pgtable_cache_init() on both archs. However, Tony Luck thought it might be useful to have a general purpose slab cache with zeroed pages. And other architectures might decide to use it for their page tables too. Consequently here's a patch that puts this functionality in slab.c. Signed-off-by: Martin K. Petersen -- Martin K. Petersen Wild Open Source, Inc. mkp@wildopensource.com http://www.wildopensource.com/ diff -urN -X /usr/people/mkp/bin/dontdiff linux-pristine/include/linux/slab.h zero-slab/include/linux/slab.h --- linux-pristine/include/linux/slab.h 2004-10-11 14:57:20.000000000 -0700 +++ zero-slab/include/linux/slab.h 2004-10-13 17:49:29.000000000 -0700 @@ -115,6 +115,7 @@ extern kmem_cache_t *signal_cachep; extern kmem_cache_t *sighand_cachep; extern kmem_cache_t *bio_cachep; +extern kmem_cache_t *zero_page_cachep; extern atomic_t slab_reclaim_pages; diff -urN -X /usr/people/mkp/bin/dontdiff linux-pristine/mm/slab.c zero-slab/mm/slab.c --- linux-pristine/mm/slab.c 2004-10-11 14:57:20.000000000 -0700 +++ zero-slab/mm/slab.c 2004-10-13 17:49:57.000000000 -0700 @@ -716,6 +716,13 @@ static struct notifier_block cpucache_notifier = { &cpuup_callback, NULL, 0 }; +kmem_cache_t *zero_page_cachep; + +static void zero_page_ctor(void *pte, kmem_cache_t *cache, unsigned long flags) +{ + memset(pte, 0, PAGE_SIZE); +} + /* Initialisation. * Called after the gfp() functions have been enabled, and before smp_init(). */ @@ -837,6 +844,16 @@ /* The reap timers are started later, with a module init call: * That part of the kernel is not yet operational. */ + + /* General purpose cache of zeroed pages */ + zero_page_cachep = kmem_cache_create("zero_page_cache", + PAGE_SIZE, 0, + SLAB_HWCACHE_ALIGN | + SLAB_MUST_HWCACHE_ALIGN, + zero_page_ctor, + NULL); + if (!zero_page_cachep) + panic("could not create zero_page_cache!\n"); } static int __init cpucache_init(void)