From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id B224CA320B for ; Mon, 21 Oct 2019 15:04:24 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id E49841BDFD; Mon, 21 Oct 2019 15:04:23 +0200 (CEST) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by dpdk.org (Postfix) with ESMTP id 5E4ED5681 for ; Mon, 21 Oct 2019 15:04:22 +0200 (CEST) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Oct 2019 06:04:21 -0700 X-IronPort-AV: E=Sophos;i="5.67,323,1566889200"; d="scan'208";a="191104797" Received: from bricha3-mobl.ger.corp.intel.com ([10.237.221.95]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 21 Oct 2019 06:04:19 -0700 Date: Mon, 21 Oct 2019 14:04:16 +0100 From: Bruce Richardson To: "Varghese, Vipin" Cc: "Loftus, Ciara" , 'Stephen Hemminger' , "'dev@dpdk.org'" , "Ye, Xiaolong" , "Laatz, Kevin" , "Yigit, Ferruh" Message-ID: <20191021130416.GB942@bricha3-MOBL.ger.corp.intel.com> References: <20190930164205.19419-1-ciara.loftus@intel.com> <20190930164205.19419-3-ciara.loftus@intel.com> <20190930101137.4919f93e@hermes.lan> <74F120C019F4A64C9B78E802F6AD4CC279226C6C@IRSMSX106.ger.corp.intel.com> <74F120C019F4A64C9B78E802F6AD4CC27924737D@IRSMSX106.ger.corp.intel.com> <4C9E0AB70F954A408CC4ADDBF0F8FA7D4D3DCF94@BGSMSX101.gar.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C9E0AB70F954A408CC4ADDBF0F8FA7D4D3DCF94@BGSMSX101.gar.corp.intel.com> User-Agent: Mutt/1.12.1 (2019-06-15) Subject: Re: [dpdk-dev] [PATCH v2 2/3] net/af_xdp: support pinning of IRQs 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Mon, Oct 21, 2019 at 01:52:27PM +0100, Varghese, Vipin wrote: > Hi Ciara, > > snipped > > > > ifaces no pinning pinning > > 1 9059100 9171612 > > 2 9261635 18376552 > > 3 9332804 27696702 > > > > For the no-pinning case, all IRQs are landing on the default core 0, which > > results in very poor scaling versus the pinned case where scaling is linear. > > Thanks for the information, but a question here `Is the reason for landing all IRQ on core '0' is because the Kernel CMD line 'isol or no interupts' is done for all expect core 0?` > > If the cores are not isolated and no interrupts are redirected; normally `cat /proc/interrupts` shows IRQ mask to cores. Depending upon FDIR (intel X522 and X710) this could be core 0 or 'n-1'? > Yes, the interrupt pinning default is somewhat dependent on the exact setup, but the fact remains that in just about any setup the interrupts for an AF_XDP queue are unlikely to end up on the exactly the one core that the user wants them on. This is what makes this patch so necessary, both from a usability and performance point of view. In the absense of alternatives, I really think this patch should be merged, since with more than one point the difference between having correctly or incorrectly pinned interrupts is huge. I'd also point out that in my testing the interrupts need to be pinned each and every time an app is run - it's not a set once and forget thing. This ability to have the driver pin the interrupts for the user would be a big timesaver for developers too, who may be constantly re-running apps when testing. Regards, /Bruce