From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 284827EB0 for ; Thu, 4 Dec 2014 12:04:11 +0100 (CET) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP; 04 Dec 2014 03:03:33 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="424988292" Received: from irsmsx152.ger.corp.intel.com ([163.33.192.66]) by FMSMGA003.fm.intel.com with ESMTP; 04 Dec 2014 02:53:13 -0800 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.144]) by IRSMSX152.ger.corp.intel.com ([169.254.6.56]) with mapi id 14.03.0195.001; Thu, 4 Dec 2014 11:03:32 +0000 From: "Ananyev, Konstantin" To: Thomas Monjalon , Olivier MATZ Thread-Topic: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM Thread-Index: AQHQDu5Csn4rdRtSMEuKWiThOnkfhJx9OYaAgAAV4YCAABxsgIABPOtwgACRSjCAAAbgAIAAA4Qw Date: Thu, 4 Dec 2014 11:03:31 +0000 Message-ID: <2601191342CEEE43887BDE71AB977258213BC7F9@IRSMSX105.ger.corp.intel.com> References: <1417532767-1309-1-git-send-email-jijiang.liu@intel.com> <1ED644BD7E0A5F4091CF203DAFB8E4CC01D9FF2B@SHSMSX101.ccr.corp.intel.com> <2601191342CEEE43887BDE71AB977258213BC6F2@IRSMSX105.ger.corp.intel.com> <2324692.x6b6svf072@xps13> In-Reply-To: <2324692.x6b6svf072@xps13> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM 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: Thu, 04 Dec 2014 11:04:15 -0000 Hi Thomas, > -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > Sent: Thursday, December 04, 2014 10:45 AM > To: Ananyev, Konstantin; Olivier MATZ > Cc: dev@dpdk.org; Liu, Jijiang > Subject: Re: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and rep= alce PKT_TX_VXLAN_CKSUM >=20 > Hi, >=20 > 2014-12-04 10:23, Ananyev, Konstantin: > > From: Liu, Jijiang > > > From: Olivier MATZ [mailto:olivier.matz@6wind.com] > > > > On 12/03/2014 01:59 PM, Ananyev, Konstantin wrote: > > > > >> I still think having a flag IPV4 + another flag IP_CHECKSUM is n= ot > > > > >> appropriate. > > > > > > > > > > Sorry, didn't get you here. > > > > > Are you talking about our discussion should PKT_TX_IP_CKSUM and > > > > > PKT_TX_IPV4 be mutually exclusive or not? > > > > > > > > Yes > > > > > > > > >> I though Konstantin agreed on other flags, but I may have > > > > >> misunderstood: > > > > >> > > > > >> http://dpdk.org/ml/archives/dev/2014-November/009070.html > > > > > > > > > > In that mail, I was talking about my suggestion to make PKT_TX_I= P_CKSUM, > > > > PKT_TX_IPV4 and PKT_TX_IPV6 to occupy 2 bits. > > > > > Something like: > > > > > #define PKT_TX_IP_CKSUM (1 << X) > > > > > #define PKT_TX_IPV6 (2 << X) > > > > > #define PKT_TX_IPV4 (3 << X) > > > > > > > > > > "Even better, if we can squeeze these 3 flags into 2 bits. > > > > > Would save us 2 bits, plus might be handy, as in the PMD you can = do: > > > > > > > > > > switch (ol_flags & TX_L3_MASK) { > > > > > case TX_IPV4: > > > > > ... > > > > > break; > > > > > case TX_IPV6: > > > > > ... > > > > > break; > > > > > case TX_IP_CKSUM: > > > > > ... > > > > > break; > > > > > }" > > > > > > > > > > As you pointed out, it will break backward compatibility. > > > > > I agreed with that and self-NACKed it. > > > > > > > > ok, so we are back between: > > > > > > > > 1/ (Jijiang's patch) > > > > PKT_TX_IP_CKSUM /* packet is IPv4, and we want hw cksum */ > > > > PKT_TX_IPV6 /* packet is IPv6 */ > > > > PKT_TX_IPV4 /* packet is IPv4, and we don't want hw cksum */ > > > > > > > > with PKT_TX_IP_CKSUM and PKT_TX_IPV4 exclusive > > > > > > > > and > > > > > > > > 2/ > > > > PKT_TX_IP_CKSUM /* we want hw IP cksum */ > > > > PKT_TX_IPV6 /* packet is IPv6 */ > > > > PKT_TX_IPV4 /* packet is IPv4 */ > > > > > > > > with PKT_TX_IP_CKSUM implies PKT_TX_IPV4 > > > > > > > > > > > > Solution 2/ looks better from a user point of view. Anyone else has= an opinion? > > > > > > Let's think about these IPv4/6 flags in terms of checksum and IP vers= ion/type, > > > > > > 1. For IPv6 > > > IP checksum is meaningful only for IPv4, so we define 'PKT_TX_IPV6 = /* packet is IPv6 */' to tell driver/HW that this is IPV6 > packet, > > > here we don't talk about the checksum for IPv6 as it is meaningless. = Right? > > > > > > PKT_TX_IPV6 /* packet is IPv6 */ ------ IP type: v6; HW= checksum: meaningless > > > > > > 2. For IPv4, > > > My patch: > > > > > > PKT_TX_IP_CKSUM /* packet is IPv4, and we want hw cksum */----------= ----------------IP type: v4; HW checksum: Yes > > > PKT_TX_IPV4 /* packet is IPv4, and we don't want hw cksum */ ---= -------------------- IP type: v4; HW checksum: No > > > > > > You want: > > > PKT_TX_IP_CKSUM /* we want hw IP cksum */-------------------------- = IP type: v4; HW checksum: Yes > > > PKT_TX_IPV4 /* packet is IPv4*/ ------------------------ IP typ= e: v4; HW checksum: yes or no? > > > = driver/HW don't know, just know this is p= acket with IPv4 header. > > > = HW checksum: meaningless?? > > > > Yep, that's why I also don't like that suggestion: PKT_TX_IPV4 itself d= oesn't contain all information. > > PMD will have to check PKT_TX_IP_CKSUM anyway. >=20 > I prefer solution 2 because a flag should bring only 1 information. Why is that? For example in mbuf we already have a flag that brings 2 thing= s: PKT_TX_IP_CKSUM /* packet is IPv4, and we want hw cksum */ If it would be possible to compress 10 meanings into 1 bit, I would happily= do that. Unfortunately, it is rarely possible :) > It's simply saner and could fit to more situations in the future. Could you give an example of such situation? I personally couldn't come up with the case where #2 would have any real ad= vantage.=20 Konstantin >=20 > -- > Thomas