user/sven/linux.git/include/linux/slub_def.h, branch v3.0.85

slub: Deal with hyperthetical case of PAGE_SIZE > 2M

2011-05-21T09:53:53Z

kmalloc_index() currently returns -1 if the PAGE_SIZE is larger than 2M which seems to cause some concern since the callers do not check for -1. Insert a BUG() and add a comment to the -1 explaining that the code cannot be reached. Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg

slub: Remove CONFIG_CMPXCHG_LOCAL ifdeffery

2011-05-07T17:25:38Z

Remove the #ifdefs. This means that the irqsafe_cpu_cmpxchg_double() is used everywhere. There may be performance implications since: A. We now have to manage a transaction ID for all arches B. The interrupt holdoff for arches not supporting CONFIG_CMPXCHG_LOCAL is reduced to a very short irqoff section. There are no multiple irqoff/irqon sequences as a result of this change. Even in the fallback case we only have to do one disable and enable like before. Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg

slub: Add statistics for this_cmpxchg_double failures

2011-03-22T18:48:04Z

Add some statistics for debugging. Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg

Merge branch 'slub/lockless' into for-linus

2011-03-20T16:13:26Z

Conflicts: include/linux/slub_def.h

slub: automatically reserve bytes at the end of slab

2011-03-11T16:06:34Z

There is no "struct" for slub's slab, it shares with struct page. But struct page is very small, it is insufficient when we need to add some metadata for slab. So we add a field "reserved" to struct kmem_cache, when a slab is allocated, kmem_cache->reserved bytes are automatically reserved at the end of the slab for slab's metadata. Changed from v1: Export the reserved field via sysfs Acked-by: Christoph Lameter Signed-off-by: Lai Jiangshan Signed-off-by: Pekka Enberg

Lockless (and preemptless) fastpaths for slub

2011-03-11T15:42:49Z

Use the this_cpu_cmpxchg_double functionality to implement a lockless allocation algorithm on arches that support fast this_cpu_ops. Each of the per cpu pointers is paired with a transaction id that ensures that updates of the per cpu information can only occur in sequence on a certain cpu. A transaction id is a "long" integer that is comprised of an event number and the cpu number. The event number is incremented for every change to the per cpu state. This means that the cmpxchg instruction can verify for an update that nothing interfered and that we are updating the percpu structure for the processor where we picked up the information and that we are also currently on that processor when we update the information. This results in a significant decrease of the overhead in the fastpaths. It also makes it easy to adopt the fast path for realtime kernels since this is lockless and does not require the use of the current per cpu area over the critical section. It is only important that the per cpu area is current at the beginning of the critical section and at the end. So there is no need even to disable preemption. Test results show that the fastpath cycle count is reduced by up to ~ 40% (alloc/free test goes from ~140 cycles down to ~80). The slowpath for kfree adds a few cycles. Sadly this does nothing for the slowpath which is where the main issues with performance in slub are but the best case performance rises significantly. (For that see the more complex slub patches that require cmpxchg_double) Kmalloc: alloc/free test Before: 10000 times kmalloc(8)/kfree -> 134 cycles 10000 times kmalloc(16)/kfree -> 152 cycles 10000 times kmalloc(32)/kfree -> 144 cycles 10000 times kmalloc(64)/kfree -> 142 cycles 10000 times kmalloc(128)/kfree -> 142 cycles 10000 times kmalloc(256)/kfree -> 132 cycles 10000 times kmalloc(512)/kfree -> 132 cycles 10000 times kmalloc(1024)/kfree -> 135 cycles 10000 times kmalloc(2048)/kfree -> 135 cycles 10000 times kmalloc(4096)/kfree -> 135 cycles 10000 times kmalloc(8192)/kfree -> 144 cycles 10000 times kmalloc(16384)/kfree -> 754 cycles After: 10000 times kmalloc(8)/kfree -> 78 cycles 10000 times kmalloc(16)/kfree -> 78 cycles 10000 times kmalloc(32)/kfree -> 82 cycles 10000 times kmalloc(64)/kfree -> 88 cycles 10000 times kmalloc(128)/kfree -> 79 cycles 10000 times kmalloc(256)/kfree -> 79 cycles 10000 times kmalloc(512)/kfree -> 85 cycles 10000 times kmalloc(1024)/kfree -> 82 cycles 10000 times kmalloc(2048)/kfree -> 82 cycles 10000 times kmalloc(4096)/kfree -> 85 cycles 10000 times kmalloc(8192)/kfree -> 82 cycles 10000 times kmalloc(16384)/kfree -> 706 cycles Kmalloc: Repeatedly allocate then free test Before: 10000 times kmalloc(8) -> 211 cycles kfree -> 113 cycles 10000 times kmalloc(16) -> 174 cycles kfree -> 115 cycles 10000 times kmalloc(32) -> 235 cycles kfree -> 129 cycles 10000 times kmalloc(64) -> 222 cycles kfree -> 120 cycles 10000 times kmalloc(128) -> 343 cycles kfree -> 139 cycles 10000 times kmalloc(256) -> 827 cycles kfree -> 147 cycles 10000 times kmalloc(512) -> 1048 cycles kfree -> 272 cycles 10000 times kmalloc(1024) -> 2043 cycles kfree -> 528 cycles 10000 times kmalloc(2048) -> 4002 cycles kfree -> 571 cycles 10000 times kmalloc(4096) -> 7740 cycles kfree -> 628 cycles 10000 times kmalloc(8192) -> 8062 cycles kfree -> 850 cycles 10000 times kmalloc(16384) -> 8895 cycles kfree -> 1249 cycles After: 10000 times kmalloc(8) -> 190 cycles kfree -> 129 cycles 10000 times kmalloc(16) -> 76 cycles kfree -> 123 cycles 10000 times kmalloc(32) -> 126 cycles kfree -> 124 cycles 10000 times kmalloc(64) -> 181 cycles kfree -> 128 cycles 10000 times kmalloc(128) -> 310 cycles kfree -> 140 cycles 10000 times kmalloc(256) -> 809 cycles kfree -> 165 cycles 10000 times kmalloc(512) -> 1005 cycles kfree -> 269 cycles 10000 times kmalloc(1024) -> 1999 cycles kfree -> 527 cycles 10000 times kmalloc(2048) -> 3967 cycles kfree -> 570 cycles 10000 times kmalloc(4096) -> 7658 cycles kfree -> 637 cycles 10000 times kmalloc(8192) -> 8111 cycles kfree -> 859 cycles 10000 times kmalloc(16384) -> 8791 cycles kfree -> 1173 cycles Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg

slub: min_partial needs to be in first cacheline

2011-03-11T15:42:49Z

It is used in unfreeze_slab() which is a performance critical function. Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg

slub tracing: move trace calls out of always inlined functions to reduce kernel code size

2010-11-06T07:04:33Z

Having the trace calls defined in the always inlined kmalloc functions in include/linux/slub_def.h causes a lot of code duplication as the trace functions get instantiated for each kamalloc call site. This can simply be removed by pushing the trace calls down into the functions in slub.c. On my x86_64 built this patch shrinks the code size of the kernel by approx 36K and also shrinks the code size of many modules -- too many to list here ;) size vmlinux (2.6.36) reports text data bss dec hex filename 5410611 743172 828928 6982711 6a8c37 vmlinux 5373738 744244 828928 6946910 6a005e vmlinux + patch The resulting kernel has had some testing & kmalloc trace still seems to work. This patch - moves trace_kmalloc out of the inlined kmalloc() and pushes it down into kmem_cache_alloc_trace() so this it only get instantiated once. - rename kmem_cache_alloc_notrace() to kmem_cache_alloc_trace() to indicate that now is does have tracing. (maybe this would better being called something like kmalloc_kmem_cache ?) - adds a new function kmalloc_order() to handle allocation and tracing of large allocations of page order. - removes tracing from the inlined kmalloc_large() replacing them with a call to kmalloc_order(); - move tracing out of inlined kmalloc_node() and pushing it down into kmem_cache_alloc_node_trace - rename kmem_cache_alloc_node_notrace() to kmem_cache_alloc_node_trace() - removes the include of trace/events/kmem.h from slub_def.h. v2 - keep kmalloc_order_trace inline when !CONFIG_TRACE Signed-off-by: Richard Kennedy Signed-off-by: Pekka Enberg

slub: Enable sysfs support for !CONFIG_SLUB_DEBUG

2010-10-06T13:54:36Z

Currently disabling CONFIG_SLUB_DEBUG also disabled SYSFS support meaning that the slabs cannot be tuned without DEBUG. Make SYSFS support independent of CONFIG_SLUB_DEBUG Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg

slub: reduce differences between SMP and NUMA

2010-10-02T07:44:10Z

Reduce the #ifdefs and simplify bootstrap by making SMP and NUMA as much alike as possible. This means that there will be an additional indirection to get to the kmem_cache_node field under SMP. Acked-by: David Rientjes Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg