From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 29 Jul 2002 17:56:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 29 Jul 2002 17:56:15 -0400 Received: from verein.lst.de ([212.34.181.86]:31251 "EHLO verein.lst.de") by vger.kernel.org with ESMTP id ; Mon, 29 Jul 2002 17:56:13 -0400 Date: Mon, 29 Jul 2002 23:59:32 +0200 From: Christoph Hellwig To: Linus Torvalds Cc: linux-kernel@vger.kernel.org Subject: [PATCH] implement kmem_cache_size() Message-ID: <20020729235932.A6889@lst.de> Mail-Followup-To: Christoph Hellwig , Linus Torvalds , linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Currently there is no way to find out the effective object size of a slab cache. XFS has lots of IRIX-derived code that want to do zalloc() style allocations on zones (which are implemented as slab caches in XFS/Linux) and thus needs to know about it. There are three ways do implement it: a) implement kmem_cache_zalloc b) make the xfs zone a struct of kmem_cache_t and a size variable c) implement kmem_cache_size The current XFS tree does a) but I absolutely don't like it as encourages people to use kmem_cache_zalloc for new code instead of thinking about how to utilize slab object reuse. b) would be easy, but I guess kmem_cache_size is usefull enough to get into the kernel. Here's the patch: --- a/include/linux/slab.h Mon Jul 15 16:39:25 2002 +++ b/include/linux/slab.h Mon Jul 15 16:39:25 2002 @@ -57,6 +57,7 @@ extern int kmem_cache_shrink(kmem_cache_t *); extern void *kmem_cache_alloc(kmem_cache_t *, int); extern void kmem_cache_free(kmem_cache_t *, void *); +extern unsigned int kmem_cache_size(kmem_cache_t *); extern void *kmalloc(size_t, int); extern void kfree(const void *); --- a/kernel/ksyms.c Mon Jul 15 16:39:25 2002 +++ b/kernel/ksyms.c Mon Jul 15 16:39:25 2002 @@ -105,6 +105,7 @@ EXPORT_SYMBOL(kmem_cache_shrink); EXPORT_SYMBOL(kmem_cache_alloc); EXPORT_SYMBOL(kmem_cache_free); +EXPORT_SYMBOL(kmem_cache_size); EXPORT_SYMBOL(kmalloc); EXPORT_SYMBOL(kfree); EXPORT_SYMBOL(vfree); --- a/mm/slab.c Mon Jul 15 16:39:25 2002 +++ b/mm/slab.c Mon Jul 15 16:39:25 2002 @@ -1637,6 +1637,15 @@ local_irq_restore(flags); } +unsigned int kmem_cache_size(kmem_cache_t *cachep) +{ +#if DEBUG + if (cachep->flags & SLAB_RED_ZONE) + return (cachep->objsize - 2*BYTES_PER_WORD); +#endif + return cachep->objsize; +} + kmem_cache_t * kmem_find_general_cachep (size_t size, int gfpflags) { cache_sizes_t *csizep = cache_sizes;