From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752131AbbIQVRR (ORCPT ); Thu, 17 Sep 2015 17:17:17 -0400 Received: from mail-by2on0142.outbound.protection.outlook.com ([207.46.100.142]:41153 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751260AbbIQVRP convert rfc822-to-8bit (ORCPT ); Thu, 17 Sep 2015 17:17:15 -0400 X-Greylist: delayed 74638 seconds by postgrey-1.27 at vger.kernel.org; Thu, 17 Sep 2015 17:17:15 EDT From: KY Srinivasan To: David Miller CC: "David.Laight@ACULAB.COM" , "alexander.duyck@gmail.com" , Haiyang Zhang , "vkuznets@redhat.com" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "jasowang@redhat.com" Subject: RE: [PATCH net-next RFC] net: increase LL_MAX_HEADER for Hyper-V Thread-Topic: [PATCH net-next RFC] net: increase LL_MAX_HEADER for Hyper-V Thread-Index: AQHQ8Jdrp1Mkwb76akCmi3unx8nMnp4/UsgAgAAEhICAABfyIIAAP8MAgAAEDQCAALQjAIAAY6KwgABH8QCAAALoEIAAEvqAgAACrHA= Date: Thu, 17 Sep 2015 21:16:24 +0000 Message-ID: References: <20150917.115218.655587837796826886.davem@davemloft.net> <20150917.131037.2286760949122849895.davem@davemloft.net> In-Reply-To: <20150917.131037.2286760949122849895.davem@davemloft.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=kys@microsoft.com; x-originating-ip: [2601:600:8c01:121d:61be:33da:497f:2c22] x-microsoft-exchange-diagnostics: 1;BY2PR0301MB0776;5:e9sK+t0oKteSjxY7g8hgaKJsI0RWmyFjpG/dLHsdDaIwkSLYombDAEKf4//TpySbwXcSH3ijy3iiH5T0g0CV5/GnNg6nLVGK4iwqoCPXeCrRBikGJQOHGMXmSq8QWcfJQeU4H+kVpDoLdaG7MwMv1Q==;24:d/89Ym3z4tzQrSHgH6nnm2bvKz1KCMbIhcY1LLMoqhdWi4sEycKtV5QqD4mM/BQJOSq64ewGy6N90KKyKEw4s6SPiDuUM7TkvTW5BSDnNdY=;20:13Pp9Ae7xORG0W0UoI5lIWLL0uc707xyQ/gmZMxoTyAR92RbCRnvw5dJrZlqSjhTpRiU9eT9Up5ISbM/d3BJAQ== x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:BY2PR0301MB0776; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(108003899814671); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(61425019)(601004)(2401001)(520078)(520075)(520058)(5005006)(8121501046)(3002001)(61426019)(61427019);SRVR:BY2PR0301MB0776;BCL:0;PCL:0;RULEID:;SRVR:BY2PR0301MB0776; x-forefront-prvs: 07025866F6 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(377454003)(189002)(13464003)(199003)(99286002)(64706001)(93886004)(10400500002)(10090500001)(189998001)(10290500002)(19580405001)(33656002)(19580395003)(5004730100002)(105586002)(5002640100001)(106116001)(5005710100001)(106356001)(5007970100001)(101416001)(86612001)(5001960100002)(110136002)(46102003)(5001860100001)(8990500004)(5003600100002)(86362001)(92566002)(5001830100001)(97736004)(4001540100001)(81156007)(50986999)(76576001)(76176999)(54356999)(40100003)(122556002)(87936001)(11100500001)(102836002)(74316001)(77096005)(68736005)(77156002)(62966003)(2900100001)(2950100001)(3826002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR0301MB0776;H:BY2PR0301MB1654.namprd03.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Sep 2015 21:16:24.3971 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY2PR0301MB0776 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: Thursday, September 17, 2015 1:11 PM > To: KY Srinivasan > Cc: David.Laight@ACULAB.COM; alexander.duyck@gmail.com; Haiyang Zhang > ; vkuznets@redhat.com; netdev@vger.kernel.org; > linux-kernel@vger.kernel.org; jasowang@redhat.com > Subject: Re: [PATCH net-next RFC] net: increase LL_MAX_HEADER for Hyper-V > > From: KY Srinivasan > Date: Thu, 17 Sep 2015 19:52:01 +0000 > > > > > > >> -----Original Message----- > >> Have a pre-cooked ring of buffers for these descriptors that you can > >> point the chip at. No per-packet allocation is necessary at all. > > > > Even if I had a ring of buffers, I would still need to manage the life cycle > > of these buffers - selecting an unused one on the transmit path and marking > > it used (atomically). > > Have one per TX ring entry, then the lifetime matches the lifetime of the > TX entry itself and therefore you need do nothing. Yes, I understand. Unfortunately, the ring buffer used on Hyper-V to send the packets to the host is not managed as a traditional TX ring entries - it is not fixed size and a given packet can wrap around and lastly, I think the management of space on the ring buffer is not tied to the act of completing the send operation. That is why we have an explicit "send complete" message. I am working on moving the model to more closely match the hardware model but it will take some time. For now, I will implement a very light weight mechanism for managing the additional memory needed. Regards, K. Y > > That's the whole idea.