Re: [PATCH] mlx4: Use GFP_NOFS calls during the ipoib TX path when creating the QP

From: Jiri Kosina
Date: Tue Feb 25 2014 - 17:40:51 EST


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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