Re: [PATCH 3/5] perf core: Prepare writing into ring buffer from end

[Wangnan (F)]

On 2016/3/24 3:25, Alexei Starovoitov wrote:
> On Wed, Mar 23, 2016 at 06:08:41PM +0800, Wangnan (F) wrote:
> > 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
> Wang, when you respin, please add all perf analysis that you've
> done and the reasons to do it this way to commit log
> to make sure it stays in git history.
>
> I've reviewed it in the past and looks like the patches didn't
> change over the last months. So still ack, I believe
> overwrite buffers is a great feature.
Can I add your Acked-by in all these 5 patches?

Thank you.