Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753364AbaBYWzQ (ORCPT ); Tue, 25 Feb 2014 17:55:16 -0500 Received: from cantor2.suse.de ([195.135.220.15]:60149 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751380AbaBYWzO (ORCPT ); Tue, 25 Feb 2014 17:55:14 -0500 Date: Tue, 25 Feb 2014 23:55:10 +0100 (CET) From: Jiri Kosina To: Or Gerlitz cc: Roland Dreier , Amir Vadai , Eli Cohen , Or Gerlitz , Eugenia Emantayev , "David S. Miller" , Mel Gorman , "netdev@vger.kernel.org" , linux-kernel Subject: Re: [PATCH] mlx4: Use GFP_NOFS calls during the ipoib TX path when creating the QP In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 26 Feb 2014, Or Gerlitz wrote: > 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 [ ... snip ... ] > > 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? That definitely can be verified, and I am putting it on my TODO list. But let's make sure that we don't diverge from the original problem too much. Simple fact is that the deadlock is there when using connected mode, and there is nothing preventing users from using it this way, therefore I believe it should be fixed one way or another. If the problem is still there in datagram mode (which, as far as my understanding of the code goes, is not the case), it should be fixed as well, but that's a different story. Thanks, -- Jiri Kosina SUSE Labs -- 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/