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From: Peter Zijlstra <peterz@infradead.org>
To: Wang Nan <wangnan0@huawei.com>
Cc: mingo@redhat.com, linux-kernel@vger.kernel.org,
	He Kuang <hekuang@huawei.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Brendan Gregg <brendan.d.gregg@gmail.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Namhyung Kim <namhyung@kernel.org>, Zefan Li <lizefan@huawei.com>,
	pi3orama@163.com
Subject: Re: [PATCH 3/5] perf core: Prepare writing into ring buffer from end
Date: Wed, 23 Mar 2016 10:50:07 +0100	[thread overview]
Message-ID: <20160323095007.GW6344@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1457949585-191064-4-git-send-email-wangnan0@huawei.com>

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.

  reply	other threads:[~2016-03-23  9:50 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-14  9:59 [PATCH 0/5] perf core: Support overwrite ring buffer Wang Nan
2016-03-14  9:59 ` [PATCH 1/5] perf core: Introduce new ioctl options to pause and resume " Wang Nan
2016-03-23  9:16   ` Peter Zijlstra
2016-03-23  9:33     ` Wangnan (F)
2016-03-23  9:52       ` Peter Zijlstra
2016-03-23 12:43       ` Vince Weaver
2016-10-21  7:06       ` Michael Kerrisk (man-pages)
2016-10-21  7:13         ` Wangnan (F)
2016-10-21  8:55           ` Michael Kerrisk (man-pages)
2016-03-14  9:59 ` [PATCH 2/5] perf core: Set event's default overflow_handler Wang Nan
2016-03-23 17:50   ` Peter Zijlstra
2016-03-23 18:13     ` Will Deacon
2016-03-23 19:13       ` Peter Zijlstra
2016-03-23 19:29       ` Peter Zijlstra
2016-03-24  9:58         ` Will Deacon
2016-03-24 10:42           ` Peter Zijlstra
2016-03-14  9:59 ` [PATCH 3/5] perf core: Prepare writing into ring buffer from end Wang Nan
2016-03-23  9:50   ` Peter Zijlstra [this message]
2016-03-23 10:08     ` Wangnan (F)
2016-03-23 19:25       ` Alexei Starovoitov
2016-03-24  3:48         ` Wangnan (F)
2016-03-24 17:29           ` Alexei Starovoitov
2016-03-25 12:26     ` Wangnan (F)
2016-03-25 12:36       ` Wangnan (F)
2016-03-25 14:14         ` Wangnan (F)
2016-03-27 15:20           ` Peter Zijlstra
2016-03-27 15:30             ` pi3orama
2016-03-28  1:07               ` Wangnan (F)
2016-03-28  1:58                 ` Wangnan (F)
2016-03-28  2:58                   ` Wangnan (F)
2016-03-14  9:59 ` [PATCH 4/5] perf core: Add backward attribute to perf event Wang Nan
2016-03-14  9:59 ` [PATCH 5/5] perf core: Reduce perf event output overhead by new overflow handler Wang Nan
2016-03-23 10:02   ` Peter Zijlstra
  -- strict thread matches above, loose matches on Subject: below --
2016-01-25  8:33 [PATCH 0/5] perf core: Read from overwrite ring buffer Wang Nan
2016-01-25  8:33 ` [PATCH 3/5] perf core: Prepare writing into ring buffer from end Wang Nan

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