From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id A73F41B2EB for ; Fri, 20 Oct 2017 03:02:44 +0200 (CEST) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Oct 2017 18:02:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,404,1503385200"; d="scan'208";a="1232952933" Received: from fmsmsx104.amr.corp.intel.com ([10.18.124.202]) by fmsmga002.fm.intel.com with ESMTP; 19 Oct 2017 18:02:43 -0700 Received: from fmsmsx117.amr.corp.intel.com (10.18.116.17) by fmsmsx104.amr.corp.intel.com (10.18.124.202) with Microsoft SMTP Server (TLS) id 14.3.319.2; Thu, 19 Oct 2017 18:02:43 -0700 Received: from shsmsx152.ccr.corp.intel.com (10.239.6.52) by fmsmsx117.amr.corp.intel.com (10.18.116.17) with Microsoft SMTP Server (TLS) id 14.3.319.2; Thu, 19 Oct 2017 18:02:42 -0700 Received: from shsmsx101.ccr.corp.intel.com ([169.254.1.159]) by SHSMSX152.ccr.corp.intel.com ([169.254.6.93]) with mapi id 14.03.0319.002; Fri, 20 Oct 2017 09:02:40 +0800 From: "Li, Xiaoyun" To: "Richardson, Bruce" , Thomas Monjalon CC: "Ananyev, Konstantin" , "dev@dpdk.org" , "Lu, Wenzhuo" , "Zhang, Helin" , "ophirmu@mellanox.com" Thread-Topic: [dpdk-dev] [PATCH v8 1/3] eal/x86: run-time dispatch over memcpy Thread-Index: AQHTRAIprgY4BVeLI0+Q0HvX97iHcaLoDmwAgADN1xCAAE2qAIABU4GQ///D5QCAAJH3wP//iH4AgACJLtD//35agAABBKoAADE0GyA= Date: Fri, 20 Oct 2017 01:02:39 +0000 Message-ID: References: <1507206794-79941-1-git-send-email-xiaoyun.li@intel.com> <3438028.jIYWTcBuhA@xps> <4686516.j2scn2ENsX@xps> <20171019092941.GA5780@bricha3-MOBL3.ger.corp.intel.com> In-Reply-To: <20171019092941.GA5780@bricha3-MOBL3.ger.corp.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH v8 1/3] eal/x86: run-time dispatch over memcpy X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 Oct 2017 01:02:45 -0000 > -----Original Message----- > From: Richardson, Bruce > Sent: Thursday, October 19, 2017 17:30 > To: Thomas Monjalon > Cc: Li, Xiaoyun ; Ananyev, Konstantin > ; dev@dpdk.org; Lu, Wenzhuo > ; Zhang, Helin ; > ophirmu@mellanox.com > Subject: Re: [dpdk-dev] [PATCH v8 1/3] eal/x86: run-time dispatch over > memcpy >=20 > On Thu, Oct 19, 2017 at 11:00:33AM +0200, Thomas Monjalon wrote: > > 19/10/2017 10:50, Li, Xiaoyun: > > > > > > > -----Original Message----- > > > > From: Thomas Monjalon [mailto:thomas@monjalon.net] > > > > Sent: Thursday, October 19, 2017 16:34 > > > > To: Li, Xiaoyun > > > > Cc: Ananyev, Konstantin ; > > > > Richardson, Bruce ; dev@dpdk.org; Lu, > > > > Wenzhuo ; Zhang, Helin > > > > ; ophirmu@mellanox.com > > > > Subject: Re: [dpdk-dev] [PATCH v8 1/3] eal/x86: run-time dispatch > > > > over memcpy > > > > > > > > 19/10/2017 09:51, Li, Xiaoyun: > > > > > From: Thomas Monjalon [mailto:thomas@monjalon.net] > > > > > > 19/10/2017 04:45, Li, Xiaoyun: > > > > > > > Hi > > > > > > > > > > > > > > > > > > > > The significant change of this patch is to call a > > > > > > > > > > function pointer for packet size > 128 > (RTE_X86_MEMCPY_THRESH). > > > > > > > > > The perf drop is due to function call replacing inline. > > > > > > > > > > > > > > > > > > > Please could you provide some benchmark numbers? > > > > > > > > > I ran memcpy_perf_test which would show the time cost of > > > > > > > > > memcpy. I ran it on broadwell with sse and avx2. > > > > > > > > > But I just draw pictures and looked at the trend not > > > > > > > > > computed the exact percentage. Sorry about that. > > > > > > > > > The picture shows results of copy size of 2, 4, 6, 8, 9, > > > > > > > > > 12, 16, 32, 64, 128, 192, 256, 320, 384, 448, 512, 768, > > > > > > > > > 1024, 1518, 1522, 1536, 1600, 2048, 2560, 3072, 3584, > > > > > > > > > 4096, 4608, 5120, 5632, 6144, 6656, 7168, > > > > > > > > 7680, 8192. > > > > > > > > > In my test, the size grows, the drop degrades. (Using > > > > > > > > > copy time indicates the > > > > > > > > > perf.) From the trend picture, when the size is smaller > > > > > > > > > than > > > > > > > > > 128 bytes, the perf drops a lot, almost 50%. And above > > > > > > > > > 128 bytes, it approaches the original dpdk. > > > > > > > > > I computed it right now, it shows that when greater than > > > > > > > > > 128 bytes and smaller than 1024 bytes, the perf drops abo= ut > 15%. > > > > > > > > > When above > > > > > > > > > 1024 bytes, the perf drops about 4%. > > > > > > > > > > > > > > > > > > > From a test done at Mellanox, there might be a > > > > > > > > > > performance degradation of about 15% in testpmd txonly > with AVX2. > > > > > > > > > > > > > > > > > > > > > > I did tests on X710, XXV710, X540 and MT27710 but didn't see > > > > > > performance degradation. > > > > > > > > > > > > > > I used command "./x86_64-native-linuxapp-gcc/app/testpmd -c > > > > > > > 0xf -n > > > > > > > 4 -- - > > > > > > I" and set fwd txonly. > > > > > > > I tested it on v17.11-rc1, then revert my patch and tested it= again. > > > > > > > Show port stats all and see the throughput pps. But the > > > > > > > results are similar > > > > > > and no drop. > > > > > > > > > > > > > > Did I miss something? > > > > > > > > > > > > I do not understand. Yesterday you confirmed a 15% drop with > > > > > > buffers between > > > > > > 128 and 1024 bytes. > > > > > > But you do not see this drop in your txonly tests, right? > > > > > > > > > > > Yes. The drop is using test. > > > > > Using command "make test -j" and then " ./build/app/test -c f -n = 4 " > > > > > Then run "memcpy_perf_autotest" > > > > > The results are the cycles that memory copy costs. > > > > > But I just use it to show the trend because I heard that it's > > > > > not > > > > recommended to use micro benchmarks like test_memcpy_perf for > > > > memcpy performance report as they aren't likely able to reflect > > > > performance of real world applications. > > > > > > > > Yes real applications can hide the memcpy cost. > > > > Sometimes, the cost appear for real :) > > > > > > > > > Details can be seen at > > > > > https://software.intel.com/en-us/articles/performance-optimizati > > > > > on-of- > > > > > memcpy-in-dpdk > > > > > > > > > > And I didn't see drop in testpmd txonly test. Maybe it's because > > > > > not a lot > > > > memcpy calls. > > > > > > > > It has been seen in a mlx4 use-case using more memcpy. > > > > I think 15% in micro-benchmark is too much. > > > > What can we do? Raise the threshold? > > > > > > > I think so. If there is big drop, can try raise the threshold. Maybe = 1024? > but not sure. > > > But I didn't reproduce the 15% drop on mellanox and not sure how to > verify it. > > > > I think we should focus on micro-benchmark and find a reasonnable > > threshold for a reasonnable drop tradeoff. > > > Sadly, it may not be that simple. What shows best performance for micro- > benchmarks may not show the same effect in a real application. >=20 > /Bruce Then how to measure the performance? And I cannot reproduce 15% drop on mellanox. Could the person who tested 15% drop help to do test again with 1024 thresh= old and see if there is any improvement?