Re: [patch] ipv4: don't warn about skb ack allocation failures

From: David Rientjes
Date: Fri Jun 19 2009 - 18:39:03 EST

On Fri, 19 Jun 2009, Eric W. Biederman wrote:

> But Mr. Reintjes if you really want the traces I can set up
> an script to email them to you every time it happens. Say about
> 1 a minute from my paltry little farm of machines.

Perhaps you missed my email where I suggested emitting the page allocation
warnings only when CONFIG_DEBUG_VM is enabled. It's at

We can then keep the __GFP_NOFAIL flag to indicate that the warnings
should never be emitted for that allocation, regardless of the .config.

It's funny, though, that the problem that originally started this thread
was quickly diagnosed because of these messages. As far as I know, my
suggestion to increase /proc/sys/vm/dirty_background_ratio to kick pdflush
earlier has prevented the slab allocation failures and not required
delayed acks for nfsd.

That was possible because of the page allocation failure messages that
were noticed by the user; without this evidence, the only symptom would
have been extremely slow I/O over nfs. This could involve any number of
subsystems and I doubt the first reaction would have been to enable
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