Messages in this thread Patch in this message | | | Date | Mon, 15 Jul 2002 14:51:30 +0100 | From | Christoph Hellwig <> | Subject | [PATCH] implement kmem_cache_size |
| |
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:
# This is a BitKeeper generated patch for the following project: # Project Name: Linux kernel tree # This patch format is intended for GNU patch command version 2.5 or higher. # This patch includes the following deltas: # ChangeSet 1.641 -> 1.642 # kernel/ksyms.c 1.109 -> 1.110 # include/linux/slab.h 1.11 -> 1.12 # mm/slab.c 1.21 -> 1.22 # # The following is the BitKeeper ChangeSet Log # -------------------------------------------- # 02/07/15 hch@sb.bsdonline.org 1.642 # Add a new function, kmem_cache_size to the slab allocator implementation. # # It is used to find out the effective object size of a slab cache, # which is needed to e.g. implement a zalloc() lookalike in XFS. # -------------------------------------------- # diff -Nru a/include/linux/slab.h b/include/linux/slab.h --- 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 *); diff -Nru a/kernel/ksyms.c b/kernel/ksyms.c --- 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); diff -Nru a/mm/slab.c b/mm/slab.c --- 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; - 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/
| |