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authorVaibhav Nagarnaik <vnagarnaik@google.com>2011-05-03 17:56:42 -0700
committerSteven Rostedt <rostedt@goodmis.org>2011-06-14 22:04:39 -0400
commit7ea5906405a1f3fc1c0033dfd7e02f2cfd1de5e5 (patch)
treef75e962db25ccd3efa81e1fc69ce3e60d228c7a6 /include/linux
parente7e2ee89a9dbf48d70a922d5625cd7320a27cbff (diff)
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tracing: Use NUMA allocation for per-cpu ring buffer pages
The tracing ring buffer is a group of per-cpu ring buffers where allocation and logging is done on a per-cpu basis. The events that are generated on a particular CPU are logged in the corresponding buffer. This is to provide wait-free writes between CPUs and good NUMA node locality while accessing the ring buffer. However, the allocation routines consider NUMA locality only for buffer page metadata and not for the actual buffer page. This causes the pages to be allocated on the NUMA node local to the CPU where the allocation routine is running at the time. This patch fixes the problem by using a NUMA node specific allocation routine so that the pages are allocated from a NUMA node local to the logging CPU. I tested with the getuid_microbench from autotest. It is a simple binary that calls getuid() in a loop and measures the average time for the syscall to complete. The following command was used to test: $ getuid_microbench 1000000 Compared the numbers found on kernel with and without this patch and found that logging latency decreases by 30-50 ns/call. tracing with non-NUMA allocation - 569 ns/call tracing with NUMA allocation - 512 ns/call Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Link: http://lkml.kernel.org/r/1304470602-20366-1-git-send-email-vnagarnaik@google.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/ring_buffer.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index ab38ac80b0f9..b891de96000f 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -169,7 +169,7 @@ void ring_buffer_set_clock(struct ring_buffer *buffer,
size_t ring_buffer_page_len(void *page);
-void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
+void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
size_t len, int cpu, int full);