Messages in this thread | | | Subject | Re: [PATCH 3/5] perf core: Prepare writing into ring buffer from end | From | "Wangnan (F)" <> | Date | Wed, 23 Mar 2016 18:08:41 +0800 |
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On 2016/3/23 17:50, Peter Zijlstra wrote: > On Mon, Mar 14, 2016 at 09:59:43AM +0000, Wang Nan wrote: >> Convert perf_output_begin to __perf_output_begin and make the later >> function able to write records from the end of the ring buffer. >> Following commits will utilize the 'backward' flag. >> >> This patch doesn't introduce any extra performance overhead since we >> use always_inline. > So while I agree that with __always_inline and constant propagation we > _should_ end up with the same code, we have: > > $ size defconfig-build/kernel/events/ring_buffer.o.{pre,post} > text data bss dec hex filename > 3785 2 0 3787 ecb defconfig-build/kernel/events/ring_buffer.o.pre > 3673 2 0 3675 e5b defconfig-build/kernel/events/ring_buffer.o.post > > The patch actually makes the file shrink. > > So I think we still want to have some actual performance numbers.
There are some numbers. You can find them from:
http://lkml.iu.edu/hypermail/linux/kernel/1601.2/03966.html
Thank you.
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