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From: Joerg Roedel on 10 Jul 2010 11:50
On Sat, Jul 10, 2010 at 03:52:04PM +0100, Daniel J Blueman wrote:
> On 9 July 2010 22:33, Linus Torvalds <torvalds(a)linux-foundation.org> wrote:
> > On Mon, Jul 5, 2010 at 1:35 AM, Daniel J Blueman
> > <daniel.blueman(a)gmail.com> wrote:
> >> When booting 2.6.35-rc3 on some different x86 boxes with DMA debugging
> >> enabled, I've consistently seen it exhaust the allocated entries during
> >> boot, giving 'DMA-API: debugging out of memory - disabling'.
> >>
> >> Increase number of entries to allow DMA debugging again.
> >
> > Rather than increase the default that gets allocated whenever anybody
> > enables the DMA debugging, I'd really prefer to see people use the
> > kernel command line option if they run out. After all, it's a (pretty
> > esoteric) debug option, and the number of required entries depends on
> > machine configuration. I'd rather not make the default cover a huge
> > number, when you could just add
> >
> > � dma_debug_entries=65536
> >
> > on the kernel boot command line instead for machines that want/need it..
>
> That said, I am seeing the DMA pool exhaust on a single socket Core i5
> system with Intel graphics and no other adapters - seems like a fairly
> common case. If eg 25% of developers will be using similar to this,
> maybe it's good to make DMA debugging less immediately esoteric?
>
> On the other hand, I would immediately agree if the exhaustion
> occurred on an atypical setup.

How much memory do you have in this machine? We could probably make the
number of pre-allocated entries dependent on the memory available in the
machine like Ingo suggested some time ago to avoid such problems.

Joerg

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