From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 9191D199A9 for ; Thu, 19 Oct 2017 10:51:02 +0200 (CEST) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Oct 2017 01:51:01 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,400,1503385200"; d="scan'208";a="911455723" Received: from fmsmsx103.amr.corp.intel.com ([10.18.124.201]) by FMSMGA003.fm.intel.com with ESMTP; 19 Oct 2017 01:51:00 -0700 Received: from fmsmsx151.amr.corp.intel.com (10.18.125.4) by FMSMSX103.amr.corp.intel.com (10.18.124.201) with Microsoft SMTP Server (TLS) id 14.3.319.2; Thu, 19 Oct 2017 01:51:00 -0700 Received: from shsmsx102.ccr.corp.intel.com (10.239.4.154) by FMSMSX151.amr.corp.intel.com (10.18.125.4) with Microsoft SMTP Server (TLS) id 14.3.319.2; Thu, 19 Oct 2017 01:50:59 -0700 Received: from shsmsx101.ccr.corp.intel.com ([169.254.1.159]) by shsmsx102.ccr.corp.intel.com ([169.254.2.175]) with mapi id 14.03.0319.002; Thu, 19 Oct 2017 16:50:58 +0800 From: "Li, Xiaoyun" To: Thomas Monjalon CC: "Ananyev, Konstantin" , "Richardson, Bruce" , "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//iH4AgACJLtA= Date: Thu, 19 Oct 2017 08:50:57 +0000 Message-ID: References: <1507206794-79941-1-git-send-email-xiaoyun.li@intel.com> <1661434.2yK3chXuTC@xps> <3438028.jIYWTcBuhA@xps> In-Reply-To: <3438028.jIYWTcBuhA@xps> 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: Thu, 19 Oct 2017 08:51:03 -0000 > -----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 >=20 > 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 about 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 r= eal > world applications. >=20 > Yes real applications can hide the memcpy cost. > Sometimes, the cost appear for real :) >=20 > > Details can be seen at > > https://software.intel.com/en-us/articles/performance-optimization-of- > > memcpy-in-dpdk > > > > And I didn't see drop in testpmd txonly test. Maybe it's because not a = lot > memcpy calls. >=20 > 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? >=20 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. > > > > > Another thing, I will test testpmd txonly with intel nics and > > > > > mellanox these days. > > > > > And try adjusting the RTE_X86_MEMCPY_THRESH to see if there is > > > > > any improvement. > > > > > > > > > > > > Is there someone else seeing a performance degradation?