linux-kernel - Re: GFP_ATOMIC page allocation failures.

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Date:	Fri, 4 Apr 2008 21:59:53 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	7eggert@....de
Cc:	Jeff Garzik <jeff@...zik.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chris Snook <csnook@...hat.com>,
	Dave Jones <davej@...emonkey.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	NetDev <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: GFP_ATOMIC page allocation failures.

On Friday 04 April 2008 20:52, Bodo Eggert wrote:
> Nick Piggin <nickpiggin@...oo.com.au> wrote:
> > On Thursday 03 April 2008 05:18, Jeff Garzik wrote:
> >> Turning to Nick's comment,
> >>
> >> > It's still actually nice to know how often it is happening even for
> >> > these known good sites because too much can indicate a problem and
> >> > that you could actually bring performance up by tuning some things.
> >>
> >> then create a counter or acculuation buffer somewhere.
> >>
> >> We don't need spew every time there is memory pressure of this
> >> magnitude.
> >
> > Not a complete solution. Counter would be nice, but you need backtraces
> > and want a way to more proactively warn the user/tester/developer.
> >
> > I agree that I don't exactly like adding nowarns around, and I don't
> > think places like driver writers should have to know about this stuff.
>
> What about reverse ratelimiting: If the limit is reached, a backtrace will
> be generated (and, off cause, positively ratelimited)?

I was thinking about that. I got as far as writing a simple patch to
printk  so that it would not start to trigger until it gets a 2nd event
within 'n' jiffies of the first.

But actually developers do sometimes want see the event even if it is
relatively infrequent...
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