From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <konstantin.ananyev@intel.com> Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id D27AB68AE for <dev@dpdk.org>; Fri, 1 Aug 2014 15:54:23 +0200 (CEST) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP; 01 Aug 2014 06:49:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="366721537" Received: from irsmsx103.ger.corp.intel.com ([163.33.3.157]) by FMSMGA003.fm.intel.com with ESMTP; 01 Aug 2014 06:53:15 -0700 Received: from irsmsx152.ger.corp.intel.com (163.33.192.66) by IRSMSX103.ger.corp.intel.com (163.33.3.157) with Microsoft SMTP Server (TLS) id 14.3.195.1; Fri, 1 Aug 2014 14:56:25 +0100 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.240]) by IRSMSX152.ger.corp.intel.com ([169.254.6.214]) with mapi id 14.03.0195.001; Fri, 1 Aug 2014 14:56:24 +0100 From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com> To: Neil Horman <nhorman@tuxdriver.com>, "Richardson, Bruce" <bruce.richardson@intel.com> Thread-Topic: [dpdk-dev] [PATCH 0/2] dpdk: Allow for dynamic enablement of some isolated features Thread-Index: AQHPrPIMyxOvxeKbSEaZ4mzC/qZsY5u7wZiZgAADkdA= Date: Fri, 1 Aug 2014 13:56:24 +0000 Message-ID: <2601191342CEEE43887BDE71AB9772582134F31F@IRSMSX105.ger.corp.intel.com> References: <1406665466-29654-1-git-send-email-nhorman@tuxdriver.com> <20140730210920.GB6420@localhost.localdomain> <20140731131351.GA20718@hmsreliant.think-freely.org> <5766264.li3nkTmgY6@xps13> <20140731143228.GB20718@hmsreliant.think-freely.org> <20140731181032.GC20718@hmsreliant.think-freely.org> <20140731183631.GC6420@localhost.localdomain> <20140731190117.GD20718@hmsreliant.think-freely.org> <20140731201949.GA28495@localhost.localdomain> <20140801133655.GA31979@hmsreliant.think-freely.org> In-Reply-To: <20140801133655.GA31979@hmsreliant.think-freely.org> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" <dev@dpdk.org> Subject: Re: [dpdk-dev] [PATCH 0/2] dpdk: Allow for dynamic enablement of some isolated features X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Fri, 01 Aug 2014 13:54:24 -0000 > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Neil Horman > Sent: Friday, August 01, 2014 2:37 PM > To: Richardson, Bruce > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH 0/2] dpdk: Allow for dynamic enablement of= some isolated features >=20 > On Thu, Jul 31, 2014 at 01:19:50PM -0700, Bruce Richardson wrote: > > On Thu, Jul 31, 2014 at 03:01:17PM -0400, Neil Horman wrote: > > > On Thu, Jul 31, 2014 at 11:36:32AM -0700, Bruce Richardson wrote: > > > > > > > > I think a good first step here that I can't see anyone objecting to= is > > > > to enable the ixgbe driver to use the vector code path for a generi= c > > > > x86_64 build. I've run a quick test here, and changing "_mm_popcnt_= u64" > > > > to "__builtin_popcountll" [and the include from nmmintrin to tmmint= rin] > > > > allows a compile for machine type default, and testpmd can still fo= rward > > > > packets at a good rate (roughly perf down about 10% vs native compi= le on > > > > SNB). > > > > The ACL is a tougher nut to crack, but anyone see any issues with t= hat > > > > two-line change to ixgbe_rxtx_vec.c? [Neil, since you started the p= atch > > > > set thread, do you want to submit an official patch here, or would = you prefer I > > > > do so?] > > > > > > > > > > I'm happy to do so, Though 10% performance degradation vs. using the = sse4.2 > > > instructions in that path seems significant, isn't it? Given that per= formance > > > delta, it seems like it would still be preferable to have a path that= used the > > > sse4.2 instructions when they're available. Or am I misreading what = you mean > > > when you say down 10% > > > > > > Neil > > > > > Ok, I did a little bit more testing here. Using the vector pmd compiled > > for generic x86_64 and using __builtin_popcountll is approx 35% faster > > for packet IO than the existing fast-path functions. It is also 7% (a > > bit lower than ~10% as I originally stated) slower than the existing > > native-compiled vpmd on a Sandy Bridge platform. > > > > I then ran an extra test, using EXTRA_CFLAGS=3D'-msse4.2' to turn on th= e > > extra instructions. The ~7% performance drop went to ~3%, so we would > > gain a little more with using SSE4.2, but compared to the gain from > > having the vector driver at all, it's not that much. [I don't have a > > system handy with AVX2 support to see what boosts might come from > > compiling with that instruction set enabled.] > > > > Because of this, I'd take the ~35% speed boost for now, and try and fin= d > > what would be the best general way to solve this problem across all > > libraries. Also, I think that anyone who needs that extra 4% performanc= e > > probably wants the other 3% too, and so will compile up the code from > > source using the "native" compilation target. :-) > > >=20 >=20 > Wait a moment, I'm not entirely sure what you did here. I understand tha= t you > replaced the _mm_popcnt_u64 call in the ixgbe pmd vector receive path wit= h > __builtin_popcnt, which is good, but ixgbe also uses the __mm_shuffle_epi= 8 > intrinsic which is only available with sse4.2 from what I can see. did yo= u > replace those calls with a __builtin_shuffle variant? Otherwise, how did= you > get the pmd to build? I'm asking because this is what I tried in the fir= st pass > and Konstantin gave some pretty convicing evidence that this was an unwor= kable > solution: > http://dpdk.org/ml/archives/dev/2014-July/004443.html >=20 I think that _mm_shuffle_epi8 (PSHUFB) is available starting from SSE3. So I presume, there is no need for replacement. Konstantin