From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx.bisdn.de (mx.bisdn.de [185.27.182.31]) by dpdk.org (Postfix) with ESMTP id 9AF912716 for ; Tue, 12 May 2015 02:38:35 +0200 (CEST) Received: from [192.168.1.102] (x5ce15ddb.dyn.telefonica.de [92.225.93.219]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx.bisdn.de (Postfix) with ESMTPSA id 4692BA3174 for ; Tue, 12 May 2015 02:38:35 +0200 (CEST) Message-ID: <55514B89.5090100@bisdn.de> Date: Tue, 12 May 2015 02:38:33 +0200 From: Marc Sune User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.6.0 MIME-Version: 1.0 To: dev@dpdk.org References: <554FF482.9080103@net.in.tum.de> <55512DE5.7010800@net.in.tum.de> <555138C7.5010002@net.in.tum.de> <55514927.6090704@bisdn.de> In-Reply-To: <55514927.6090704@bisdn.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] TX performance regression caused by the mbuf cachline split X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 May 2015 00:38:35 -0000 On 12/05/15 02:28, Marc Sune wrote: > > > On 12/05/15 01:18, Paul Emmerich wrote: >> Found a really simple solution that almost restores the original >> performance: just add a prefetch on alloc. For some reason, I assumed >> that this was already done since the troublesome commit I >> investigated mentioned something about prefetching... I guess the >> commit referred to the hardware prefetcher in the CPU. >> >> Adding an explicit prefetch command in the mbuf alloc function gives >> a throughput of 12.7/10.35 Mpps in my benchmark with the >> simple/full-featured tx path. >> >> DPDK 1.7.1 was at 14.1/10.7 Mpps. I guess I can live with that, since >> I'm primarily interested in the full-featured path and the drop from >> 10.7 to ~10.4 was due to another change. > > Maybe a stupid question; > > Does the performance of v1.7.1 also improve if you backport this patch > to it? Self answered... split was done in 1.8, so it is indeed stupid. Marc > > Marc > >> >> Patch: https://github.com/dpdk-org/dpdk/pull/2 >> I also sent an email to the mailing list. >> >> I also think that the rx-path could also benefit from prefetching >> somewhere. >> >> >> Paul >> >