Date: Tue, 25 Feb 2014 23:40:35 +0100 (CET)
From: Jiri Kosina <jkosina@suse.cz>
To: Or Gerlitz <or.gerlitz@gmail.com>
cc: Roland Dreier <roland@kernel.org>, Amir Vadai <amirv@mellanox.com>,
        Eli Cohen <eli@dev.mellanox.co.il>, Or Gerlitz <ogerlitz@mellanox.com>,
        Eugenia Emantayev <eugenia@mellanox.com>,
        "David S. Miller" <davem@davemloft.net>, Mel Gorman <mgorman@suse.de>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mlx4: Use GFP_NOFS calls during the ipoib TX path when
 creating the QP
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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.

> > 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.

-- 
Jiri Kosina
SUSE Labs
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