Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753509AbaBYWs7 (ORCPT ); Tue, 25 Feb 2014 17:48:59 -0500 Received: from mail-pb0-f51.google.com ([209.85.160.51]:50953 "EHLO mail-pb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751356AbaBYWs5 (ORCPT ); Tue, 25 Feb 2014 17:48:57 -0500 MIME-Version: 1.0 In-Reply-To: References: Date: Wed, 26 Feb 2014 00:48:57 +0200 Message-ID: Subject: Re: [PATCH] mlx4: Use GFP_NOFS calls during the ipoib TX path when creating the QP From: Or Gerlitz To: Jiri Kosina Cc: Roland Dreier , Amir Vadai , Eli Cohen , Or Gerlitz , Eugenia Emantayev , "David S. Miller" , Mel Gorman , "netdev@vger.kernel.org" , linux-kernel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 26, 2014 at 12:40 AM, Jiri Kosina wrote: > On Wed, 26 Feb 2014, Or Gerlitz wrote: > >>>> And what happens if you use IPoIB datagram mode, is/why the patch is >>>> needed there? >>> I admittedly am no infiniband expert, but my understanding is that in >>> principle Connected/Datagram mode is about MTU and checksum >>> offloading >> yes, the differences between the mode relate to these aspects, however > Thanks for confirming Still, even if different, I still don't see why not use datagram mode if the problem hits you only for connected mode. E.g datagram mode supports LSO/GRO and TX/RX checksum offloads which should cover on the smaller MTU vs. connected mode >> > but the TX path is the same. Please correct me if I am wrong. >> no, note that your patch only touched drivers/infiniband/ulp/ipoib/ipoib_cm.c >> which is basically compiled out if you set CONFIG_INFINIBAND_IPOIB_CM, >> so surely the TX path for the datagram vs. connected modes are >> different. > Yes, but for datagram mode, the tx_ring is allocated in a completely > different way (not from kworker), so this might be a non-issue, right? I > will have to look into it more deeply to be really sure; if you can > provide your insight, that'd be helpful. Note that even when operating in connected mode, the ipoib net-device instance can speak in datagram mode with remote nodes who don't support connected mor and/or when sending multicast -- specifically ipoib_dev_init() does the setup of the TX ring. Maybe you can just try this out and see if it works? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/