Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754436AbcCXDux (ORCPT ); Wed, 23 Mar 2016 23:50:53 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:16576 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750823AbcCXDux (ORCPT ); Wed, 23 Mar 2016 23:50:53 -0400 Subject: Re: [PATCH 3/5] perf core: Prepare writing into ring buffer from end To: Alexei Starovoitov References: <1457949585-191064-1-git-send-email-wangnan0@huawei.com> <1457949585-191064-4-git-send-email-wangnan0@huawei.com> <20160323095007.GW6344@twins.programming.kicks-ass.net> <56F26B29.8040401@huawei.com> <20160323192521.GA48575@ast-mbp.thefacebook.com> CC: Peter Zijlstra , , , He Kuang , "Alexei Starovoitov" , Arnaldo Carvalho de Melo , Brendan Gregg , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , Zefan Li , From: "Wangnan (F)" Message-ID: <56F363A6.2010603@huawei.com> Date: Thu, 24 Mar 2016 11:48:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: <20160323192521.GA48575@ast-mbp.thefacebook.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.66.109] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020203.56F3640A.002E,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 9391db4aa22c80e2fb0d9f397f38fd66 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1581 Lines: 37 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.