From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id A4CE747CE for ; Tue, 3 May 2016 12:16:43 +0200 (CEST) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga101.jf.intel.com with ESMTP; 03 May 2016 03:16:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,572,1455004800"; d="scan'208";a="696025079" Received: from bricha3-mobl3.ger.corp.intel.com ([10.237.220.29]) by FMSMGA003.fm.intel.com with SMTP; 03 May 2016 03:16:40 -0700 Received: by (sSMTP sendmail emulation); Tue, 03 May 2016 11:16:39 +0025 Date: Tue, 3 May 2016 11:16:39 +0100 From: Bruce Richardson To: "De Lara Guarch, Pablo" Cc: Jerin Jacob , "dev@dpdk.org" Message-ID: <20160503101639.GA15716@bricha3-MOBL3> References: <1462190377-26865-1-git-send-email-jerin.jacob@caviumnetworks.com> <20160503094516.GC21300@bricha3-MOBL3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Shannon Ltd. User-Agent: Mutt/1.5.23 (2014-03-12) Subject: Re: [dpdk-dev] [PATCH] app/testpmd: add packet data prefetch in macswap loop 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, 03 May 2016 10:16:44 -0000 On Tue, May 03, 2016 at 10:48:34AM +0100, De Lara Guarch, Pablo wrote: > > > > -----Original Message----- > > From: Richardson, Bruce > > Sent: Tuesday, May 03, 2016 10:45 AM > > To: Jerin Jacob > > Cc: dev@dpdk.org; De Lara Guarch, Pablo > > Subject: Re: [dpdk-dev] [PATCH] app/testpmd: add packet data prefetch in > > macswap loop > > > > On Mon, May 02, 2016 at 05:29:37PM +0530, Jerin Jacob wrote: > > > prefetch the next packet data address in advance in macswap loop > > > for performance improvement. > > > > > > Signed-off-by: Jerin Jacob > > > --- > > > app/test-pmd/macswap.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/app/test-pmd/macswap.c b/app/test-pmd/macswap.c > > > index 154889d..c10f4b5 100644 > > > --- a/app/test-pmd/macswap.c > > > +++ b/app/test-pmd/macswap.c > > > @@ -113,6 +113,9 @@ pkt_burst_mac_swap(struct fwd_stream *fs) > > > if (txp->tx_ol_flags & TESTPMD_TX_OFFLOAD_INSERT_QINQ) > > > ol_flags |= PKT_TX_QINQ_PKT; > > > for (i = 0; i < nb_rx; i++) { > > > + if (likely(i < nb_rx - 1)) > > > + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i + 1], > > > + void *)); > > > > At least on IA platforms, there is no issue with prefetching beyond the end of > > the array, since it's only a hint to the cpu. If this is true for other platforms, > > then I suggest we just drop the conditional and just always prefetch. > > That's what I thought when I saw this patch, but the problem is that the prefetch is not for pkts_burst, > but for rte_pktmbuf_mtod(pkts_burst...), so there must be a limit in nb_rx - 2, or there will be a seg fault. > > Pablo Good point, Pablo, I missed that subtlety here. /Bruce > > > > /Bruce > > > > > mb = pkts_burst[i]; > > > eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *); > > > > > > -- > > > 2.1.0 > > >