From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH v2] mbuf: fix compile by removing struct from function Date: Thu, 10 Jan 2019 22:03:16 -0800 Message-ID: <20190110220316.3937ad07@hermes.lan> References: <20190110165051.4859-1-harry.van.haaren@intel.com> <20190110180658.23302-1-harry.van.haaren@intel.com> <3EB4FA525960D640B5BDFFD6A3D891268E828A86@IRSMSX108.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "Dumitrescu, Cristian" , "Van Haaren, Harry" , "dev@dpdk.org" , "Pattan, Reshma" , "thomas@monjalon.net" , "olivier.matz@6wind.com" , Honnappa Nagarahalli To: "Gavin Hu (Arm Technology China)" Return-path: Received: from mail-pl1-f193.google.com (mail-pl1-f193.google.com [209.85.214.193]) by dpdk.org (Postfix) with ESMTP id 784AD1B857 for ; Fri, 11 Jan 2019 07:03:24 +0100 (CET) Received: by mail-pl1-f193.google.com with SMTP id y1so6279168plp.9 for ; Thu, 10 Jan 2019 22:03:24 -0800 (PST) In-Reply-To: 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 Fri, 11 Jan 2019 03:01:43 +0000 "Gavin Hu (Arm Technology China)" wrote: > > -----Original Message----- > > From: dev On Behalf Of Dumitrescu, Cristian > > Sent: Friday, January 11, 2019 2:40 AM > > To: Van Haaren, Harry ; dev@dpdk.org > > Cc: Pattan, Reshma ; thomas@monjalon.net; > > olivier.matz@6wind.com > > Subject: Re: [dpdk-dev] [PATCH v2] mbuf: fix compile by removing struct > > from function > > > > > > > > > -----Original Message----- > > > From: Van Haaren, Harry > > > Sent: Thursday, January 10, 2019 6:07 PM > > > To: dev@dpdk.org > > > Cc: Van Haaren, Harry ; Pattan, Reshma > > > ; Dumitrescu, Cristian > > > ; thomas@monjalon.net; > > > olivier.matz@6wind.com > > > Subject: [PATCH v2] mbuf: fix compile by removing struct from function > > > > > > Although C compilation works with the struct rte_mbuf_sched > > > declared inside the struct rte_mbuf namespace, C++ fails to > > > compile. > > > > > > This fix removes the temporary struct rte_mbuf_sched, instead > > > reading from the mbuf directly for each struct member. As the > > > struct is now not used directly, the C++ compiler doesn't need > > > to know about the struct, resolving the issue. > > > > > > Fixes: 5d3f72100904 ("mbuf: implement generic format for sched field") > > > > > > Signed-off-by: Harry van Haaren > > > > > > --- > > > > > > Cc: reshma.pattan@intel.com > > > Cc: cristian.dumitrescu@intel.com > > > Cc: thomas@monjalon.net > > > Cc: olivier.matz@6wind.com > > > > > > See mailing list for v1 discussion, perhaps this solution is more > > > readable due to leaving sched struct in-line in the mbuf struct. > > > --- > > > lib/librte_mbuf/rte_mbuf.h | 16 ++++++---------- > > > 1 file changed, 6 insertions(+), 10 deletions(-) > > > > > > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h > > > index bc562dc8a..1b260efd5 100644 > > > --- a/lib/librte_mbuf/rte_mbuf.h > > > +++ b/lib/librte_mbuf/rte_mbuf.h > > > @@ -2344,11 +2344,9 @@ rte_mbuf_sched_get(const struct rte_mbuf > > *m, > > > uint32_t *queue_id, > > > uint8_t *traffic_class, > > > uint8_t *color) > > > { > > > -struct rte_mbuf_sched sched = m->hash.sched; > > Did C++ complain *sched? *sched is better with less stack mem footprint. > If the pointer works, the code looks better. Using *sched will cause compiler to generate multiple references which is the real performance issue here.