netdev - Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet

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Date:	Tue, 15 Feb 2011 13:42:55 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	"Michael S. Tsirkin" <mst@...hat.com>,
	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in
 virtnet_poll

On Tue 15-02-11 21:39:03, Rusty Russell wrote:
> On Tue, 15 Feb 2011 08:55:50 pm Michal Hocko wrote:
> > On Tue 15-02-11 20:41:29, Rusty Russell wrote:
> > > On Tue, 15 Feb 2011 08:05:27 pm Michal Hocko wrote:
> > > > Hi,
> > > > we have started seeing a lot of allocator messages complaining about
> > > > failed allocations from virtnet_poll in soft IRQ. Could you consider the
> > > > following patch, please?
> > > 
> > > Do we really want to silence this?  Isn't warning about it kind of the
> > > point?  Your network is probably sucking if this happens...
> > 
> > What can user do about it? Is the low level memory allocator message
> > very much usefull for him?  Maybe we can add a printk_once in the fail
> > path with some more useful and virtio specific message.
> 
> That's an argument against ever printing any message.

Well, honestly, I do not see much point for this message but it is there
for ages so it maybe it is valueable for somebody...

> 
> What we need to know is why does this happen with virtio_net and not other
> cards?  

The machine just happened to be short on memory due to a strong memory
pressure.

> If it happens to them too, and they silently fall back, all good.
> 
> I want to make sure we're not papering over a real problem...
> 
> Thanks,
> Rusty.

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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