Re: [PATCH] Tweak tracing allocation sizes

Christoph Hellwig
2008-09-03T12:05:43Z

On Wed, Sep 03, 2008 at 09:06:54AM +0200, Andi Kleen wrote:
> On Tue, Sep 02, 2008 at 05:55:16PM -0400, Christoph Hellwig wrote:
> > On Tue, Sep 02, 2008 at 08:50:52AM +0200, Andi Kleen wrote:
> > > > alternative - maybe a very large global trace buffer that is allocated at mount
> > > > time and shared by all inodes?
> > >
> > > You could use vmalloc(). While that is also not fast it will at least
> > > not stall.
> >
> > In fact kmem_alloc first tries vmalloc, and then falls back to slab
> > when it fails. See fs/xfs/linux-2.6/kmem.c:kmem_alloc().
>
> You mean the other way around?

No, take a look at the function. I guess the intent is that vmalloc
can fail due to a full vmalloc area and kmalloc could theoretically
still scucceed.