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 A29405958 for ; Mon, 3 Nov 2014 09:11:26 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP; 03 Nov 2014 00:20:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,305,1413270000"; d="scan'208";a="630175740" Received: from pgsmsx101.gar.corp.intel.com ([10.221.44.78]) by orsmga002.jf.intel.com with ESMTP; 03 Nov 2014 00:20:37 -0800 Received: from shsmsx101.ccr.corp.intel.com (10.239.4.153) by PGSMSX101.gar.corp.intel.com (10.221.44.78) with Microsoft SMTP Server (TLS) id 14.3.195.1; Mon, 3 Nov 2014 16:18:42 +0800 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.174]) by SHSMSX101.ccr.corp.intel.com ([169.254.1.202]) with mapi id 14.03.0195.001; Mon, 3 Nov 2014 16:18:41 +0800 From: "Zhang, Helin" To: Thomas Monjalon Thread-Topic: [dpdk-dev] [PATCH v5 1/5] i40e: Use constant random hash keys Thread-Index: AQHP9zv8pzWfqVE1VkCS4aq11NQwI5xOjDAQ Date: Mon, 3 Nov 2014 08:18:40 +0000 Message-ID: References: <1413180766-12211-1-git-send-email-helin.zhang@intel.com> <1413861289-26662-1-git-send-email-helin.zhang@intel.com> <1413861289-26662-2-git-send-email-helin.zhang@intel.com> <1493143.C52zTo8RWN@xps13> In-Reply-To: <1493143.C52zTo8RWN@xps13> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] 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 1/5] i40e: Use constant random hash keys 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: Mon, 03 Nov 2014 08:11:27 -0000 Hi Thomas > -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > Sent: Monday, November 3, 2014 3:50 PM > To: Zhang, Helin > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH v5 1/5] i40e: Use constant random hash key= s >=20 > Hi Helin, >=20 > The title is a bit surprising: > - it should be about RSS RSS makes use of hash function to route received packets, though hash funct= ion can be used for other cases, e.g. Flow director. > - a constant cannot be really random ;) The hash keys are generated by libc random function. It is preparatory to a= void calling random function for each port. >=20 > 2014-10-21 11:14, Helin Zhang: > > To be simpler, and remove the race condition, it uses prepared > > constant random hash keys to replace runtime generating the hash keys. >=20 > Could you explain what is the role of rss_key_default? Hash function needs to be configured with keys, before end users configured= them with specific keys, we need to provide a default keys which is genera= ted by libc random function. The random keys can get the hash function to route the received packets to = all the queues well-proportioned. >=20 > Thanks > -- > Thomas Regards, Helin