Re: 3.7.8/amd64 full interrupt hangs due to iwlwifi under big nfs copies out

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2013-02-20 at 10:12 +0100, Johannes Berg wrote:
> On Tue, 2013-02-19 at 08:21 -0800, Eric Dumazet wrote:
> > On Tue, 2013-02-19 at 11:03 +0100, Johannes Berg wrote:
> > > On Mon, 2013-02-18 at 21:17 -0800, Eric Dumazet wrote:
> > > 
> > > > > chrome: page allocation failure: order:1, mode:0x4020
> > > > > Pid: 8730, comm: chrome Tainted: G           O 3.7.8-amd64-preempt-20121226-fixwd #1
> > > > > Call Trace:
> > > > >  <IRQ>  [<ffffffff810d5f38>] warn_alloc_failed+0x117/0x12c
> > > 
> > > > You could try to load iwlwifi with amsdu_size_8K set to 0 (disable)
> > > > 
> > > > It should hopefully use order-0 pages
> > > 
> > > It will, do that then, unfortunately it can't switch at runtime because
> > > it advertised this support to the access point or clients.
> > 
> > What are the drawbacks of setting amsdu_size_8K to 0 by default ?
> 
> We're discussing this now, the only downside would be that we couldn't
> receive 8k A-MSDUs. Thing is, practically nobody uses A-MSDU anyway, and
> even when I suspect the difference between 4k and 8k won't be huge.

OTOH, this affects the protocol, and when you really can't allocate any
order-1 pages you pointed out yourself that many other things also won't
work, so I'm not really sure it makes a big difference if we change the
driver?

johannes