Messages in this thread Patch in this message |  | | | From | Rusty Trivial Russell <> | | Subject | [TRIVIAL] implement kmem_cache_size | | Date | Fri, 26 Jul 2002 16:45:33 +1000 |
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From: Christoph Hellwig <hch@lst.de>
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.
Trivial patch to implement kmem_cache_size (doesn't change any existing code) appended:
--- trivial-2.5.28/include/linux/slab.h.orig Fri Jul 26 16:37:00 2002 +++ trivial-2.5.28/include/linux/slab.h Fri Jul 26 16:37:00 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 *); --- trivial-2.5.28/kernel/ksyms.c.orig Fri Jul 26 16:37:00 2002 +++ trivial-2.5.28/kernel/ksyms.c Fri Jul 26 16:37:00 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); --- trivial-2.5.28/mm/slab.c.orig Fri Jul 26 16:37:00 2002 +++ trivial-2.5.28/mm/slab.c Fri Jul 26 16:37:00 2002 @@ -1647,6 +1647,15 @@ 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; -- Don't blame me: the Monkey is driving - 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/
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