From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrien Mazarguil Subject: Re: [PATCH 01/12] ethdev: add API to query what/if packet type is set Date: Wed, 6 Jan 2016 11:00:53 +0100 Message-ID: <20160106100053.GJ12095@6wind.com> References: <1451544799-70776-1-git-send-email-jianfeng.tan@intel.com> <1451544799-70776-2-git-send-email-jianfeng.tan@intel.com> <20160104113814.GT3806@6wind.com> <2601191342CEEE43887BDE71AB97725836AE1002@irsmsx105.ger.corp.intel.com> <20160105161423.GE4712@autoinstall.dev.6wind.com> <2601191342CEEE43887BDE71AB97725836AE18E3@irsmsx105.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: "dev@dpdk.org" To: "Ananyev, Konstantin" Return-path: Received: from mail-wm0-f47.google.com (mail-wm0-f47.google.com [74.125.82.47]) by dpdk.org (Postfix) with ESMTP id 2AF8F9591 for ; Wed, 6 Jan 2016 11:01:12 +0100 (CET) Received: by mail-wm0-f47.google.com with SMTP id f206so53480304wmf.0 for ; Wed, 06 Jan 2016 02:01:12 -0800 (PST) Content-Disposition: inline In-Reply-To: <2601191342CEEE43887BDE71AB97725836AE18E3@irsmsx105.ger.corp.intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Tue, Jan 05, 2016 at 04:50:31PM +0000, Ananyev, Konstantin wrote: [...] > > -----Original Message----- > > From: N=C3=A9lio Laranjeiro [mailto:nelio.laranjeiro@6wind.com] [...] > > I think we miss a comment here in how those 2/6/4 values are chosen > > because, according to the mask, I expect 16 possibilities but I get > > less. It will help a lot anyone who needs to add a new type. > >=20 > > Extending the snprintf behavior above, it is best to remove the mask > > argument altogether and have rte_eth_dev_get_ptype_info() return the > > entire list every time. Applications need to iterate on the result i= n > > any case. >=20 > I think we'd better keep mask argument. > In many cases upper layer only interested in some particular subset of > all packet types that HW can recognise. > Let say l3fwd only cares about RTE_PTYPE_L3_MASK, it is not interested= in L4, > tunnelling packet types, etc. > If caller needs to know all recognised ptypes, he can set mask=3D=3D-1, > In that case all supported packet types will be returned. There are other drawbacks to the mask argument in my opinion. The API wil= l have to be updated again as soon as 32 bits aren't enough to represent al= l possible masks. We can't predict it will be large enough forever but on t= he other hand, using uint64_t seems overkill at this point. I think this use for masks should be avoided when performance does not matter much, as in this case, user application cannot know the number of entries in advance and must rely on the returned value to iterate. A helper function can be added to convert a RTE_PTYPE_* value to the laye= r it belongs to (using enum to define possible values). If we absolutely want a mean to filter returned values, I suggest we use this enum instead of the mask argument. Since it won't be a mask, it won'= t have to be updated every time a new protocol requires extending one. > > rte_eth_dev_get_ptype_info(uint8_t port_id, uint32_t ptypes[], > > size_t max_entries) > >=20 > >=20 > >=20 > > Another point, I have read the example patch (l3fwd) but I don't > > understand why the PMD is not responsible for filling the packet type= in > > the MBUF (packet parsing is done by parse_packet_type()). Why the ex= tra > > computation? >=20 > As I understand there are 3 possibilities now: > 1. HW supports ptype recognition and SW ptype parsing is never done > (--parse-ptype is not specified). > 2. HW supports ptype recognition, but and SW ptype parsing is done anyw= ay > (--parse-ptype is specified). > 3. HW doesn't support and ptype recognition, and and SW ptype parsing i= s done > (--parse-ptype is specified). >=20 > I suppose the question is what for introduce '--parse-ptype' at all? > My thought because of #2, so people can easily check what will be the p= erformance impact of SW parsing.=20 >=20 > Konstantin >=20 > >=20 > > I see it more like an offload request (as checksum, etc...) and if th= e > > NIC does not support it then the application does the necessary overl= oad. > >=20 > > Best regards, > >=20 > > -- > > N=C3=A9lio Laranjeiro > > 6WIND --=20 Adrien Mazarguil 6WIND