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[204.195.22.127]) by smtp.gmail.com with ESMTPSA id d7sm717416pfr.17.2020.03.16.12.32.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2020 12:32:56 -0700 (PDT) Date: Mon, 16 Mar 2020 12:32:53 -0700 From: Stephen Hemminger <stephen@networkplumber.org> To: "Medvedkin, Vladimir" <vladimir.medvedkin@intel.com> Cc: Morten =?UTF-8?B?QnLDuHJ1cA==?= <mb@smartsharesystems.com>, dev@dpdk.org, konstantin.ananyev@intel.com, yipeng1.wang@intel.com, sameh.gobriel@intel.com, bruce.richardson@intel.com, Suanming Mou <suanmingm@mellanox.com>, Olivier Matz <olivier.matz@6wind.com>, "Xueming(Steven) Li" <xuemingl@mellanox.com>, Andrew Rybchenko <arybchenko@solarflare.com>, Asaf Penso <asafp@mellanox.com>, Ori Kam <orika@mellanox.com> Message-ID: <20200316123253.7566d799@hermes.lan> In-Reply-To: <2baf9a76-a606-d376-dcce-b95c80fc6bb2@intel.com> References: <cover.1584360151.git.vladimir.medvedkin@intel.com> <98CBD80474FA8B44BF855DF32C47DC35C60ED7@smartserver.smartshare.dk> <2baf9a76-a606-d376-dcce-b95c80fc6bb2@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [dpdk-dev] [PATCH 0/3] add new Double Word Key hash table X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org Sender: "dev" <dev-bounces@dpdk.org> On Mon, 16 Mar 2020 18:27:40 +0000 "Medvedkin, Vladimir" <vladimir.medvedkin@intel.com> wrote: > Hi Morten, >=20 >=20 > On 16/03/2020 14:39, Morten Br=C3=B8rup wrote: > >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Vladimir Medvedkin > >> Sent: Monday, March 16, 2020 2:38 PM > >> > >> Currently DPDK has a special implementation of a hash table for > >> 4 byte keys which is called FBK hash. Unfortunately its main drawback > >> is that it only supports 2 byte values. > >> The new implementation called DWK (double word key) hash > >> supports 8 byte values, which is enough to store a pointer. > >> > >> It would also be nice to get feedback on whether to leave the old FBK > >> and new DWK implementations, or whether to deprecate the old one? =20 > > <rant on> > > > > Who comes up with these names?!? > > > > FBK (Four Byte Key) and DWK (Double Word Key) is supposed to mean the s= ame. Could you use 32 somewhere in the name instead, like in int32_t, inste= ad of using a growing list of creative synonyms for the same thing? Pretty = please, with a cherry on top! =20 >=20 >=20 > That's true, at first I named it as fbk2, but then it was decided to=20 > rename it "dwk", so that there was no confusion with the existing FBK=20 > library. Naming suggestions are welcome! >=20 > > > > And if the value size is fixed too, perhaps the name should also indica= te the value size. > > > > <rant off> > > > > It's a shame we don't have C++ class templates available in DPDK... > > > > In other news, Mellanox has sent an RFC for an "indexed memory pool" li= brary [1] to conserve memory by using uintXX_t instead of pointers, so perh= aps a variant of a 32 bit key hash library with 32 bit values (in addition = to 16 bit values in FBK and 64 bit in DWK) would be nice combination with t= hat library. > > > > [1]: http://mails.dpdk.org/archives/dev/2019-October/147513.html > > > > > > Med venlig hilsen / kind regards > > - Morten Br=C3=B8rup > > =20 Why is this different (or better) than existing rte_hash. Having more flavors is not necessarily a good thing (except in Gelato)