diff options
author | Peter Zijlstra <[email protected]> | 2013-10-31 17:36:25 +0100 |
---|---|---|
committer | Ingo Molnar <[email protected]> | 2013-11-06 12:34:22 +0100 |
commit | 524feca5e9da9e5f9e5aa5d5613b1d762db9509e (patch) | |
tree | 12052071d8db98961cc9114a183d4ee1752db0a9 | |
parent | d20a973f46ed83e0d7d24f6c512064133038e193 (diff) |
perf: Optimize perf_output_begin() -- address calculation
Rewrite the handle address calculation code to be clearer.
Saves 8 bytes on x86_64-defconfig.
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: [email protected]
Cc: Vince Weaver <[email protected]>
Cc: Victor Kaplansky <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Anton Blanchard <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
-rw-r--r-- | kernel/events/ring_buffer.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index e4d70f33792f..c52a32fa5592 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -105,7 +105,7 @@ int perf_output_begin(struct perf_output_handle *handle, { struct ring_buffer *rb; unsigned long tail, offset, head; - int have_lost; + int have_lost, page_shift; struct { struct perf_event_header header; u64 id; @@ -159,12 +159,12 @@ int perf_output_begin(struct perf_output_handle *handle, if (unlikely(head - local_read(&rb->wakeup) > rb->watermark)) local_add(rb->watermark, &rb->wakeup); - handle->page = offset >> (PAGE_SHIFT + page_order(rb)); - handle->page &= rb->nr_pages - 1; - handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1); - handle->addr = rb->data_pages[handle->page]; - handle->addr += handle->size; - handle->size = (PAGE_SIZE << page_order(rb)) - handle->size; + page_shift = PAGE_SHIFT + page_order(rb); + + handle->page = (offset >> page_shift) & (rb->nr_pages - 1); + offset &= (1UL << page_shift) - 1; + handle->addr = rb->data_pages[handle->page] + offset; + handle->size = (1UL << page_shift) - offset; if (unlikely(have_lost)) { struct perf_sample_data sample_data; |