Re: [PATCH] Tweak tracing allocation sizes

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

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.