From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Su, David W" Subject: Re: [PATCH] igb_uio: use non-threaded ISR Date: Sat, 25 Feb 2017 00:21:22 +0000 Message-ID: <3875C02542CA2945BF761013C1F5B8E57F3E7953@ORSMSX109.amr.corp.intel.com> References: <1484953699-3156-1-git-send-email-david.w.su@intel.com> <22f235a0-d991-d4b0-b72d-1a2a3d5bfa82@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable To: "Yigit, Ferruh" , "dev@dpdk.org" Return-path: Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id 8FF292BA1 for ; Sat, 25 Feb 2017 01:21:24 +0100 (CET) In-Reply-To: <22f235a0-d991-d4b0-b72d-1a2a3d5bfa82@intel.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" >-----Original Message----- >From: Yigit, Ferruh >Sent: Friday, February 24, 2017 9:55 AM >To: Su, David W ; dev@dpdk.org >Subject: Re: [dpdk-dev] [PATCH] igb_uio: use non-threaded ISR > >On 1/20/2017 11:08 PM, David Su wrote: >> This eliminates the overhead of a task switch when an interrupt arrives. > >Hi David, > >Did you test patch with l3fwd-power (or any app that uses Rx >interrupts), is there any performance gain? > Hi Ferruh, The test is a simple l2 forward app and it uses the same idle heuristic as = l3fwd-power, i.e. it enables rx interrupts and goes to sleep after about 30= 0us without receiving a packet. A packet generator is configured to send a= time stamped packet every 400us to ensure the test will go through the sle= ep-wakeup cycle with every inbound packet. The packet generator measures p= acket round trip latency with the timestamps. The average latency is more than 100us on a 2.30GHz Xeon E5-2699 v3 platfor= m with Intel X540-AT2 NIC. The long latency is mostly because the DPDK ixg= be driver enables interrupt throttling in the NIC and sets the minimum inte= r-interrupt interval to about 500us. With this patch alone, there is no si= gnificant change to the average latency, the maximum latency is reduced fro= m 418us to 392us. If interrupt throttling is not enabled (http://dpdk.org/= dev/patchwork/patch/19856/), the average latency is reduced from 17us to 14= us and the maximum latency from 30us to 21us. >> >> Signed-off-by: David Su ><...>