Re: [PATCH 4/5] kmemtrace: SLUB hooks.

Eduard - Gabriel Munteanu
2008-08-12T15:28:38Z

On Mon, Aug 11, 2008 at 05:09:34PM +0300, Pekka Enberg wrote:
> On Mon, 2008-08-11 at 09:04 -0500, Christoph Lameter wrote:
> > Eduard - Gabriel Munteanu wrote:
> >
> >
> >
> > > static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
> > > {
> > > + void *ret;
> > > +
> > > if (__builtin_constant_p(size) &&
> > > size <= PAGE_SIZE && !(flags & SLUB_DMA)) {
> > > struct kmem_cache *s = kmalloc_slab(size);
> > > @@ -239,7 +280,13 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
> > > if (!s)
> > > return ZERO_SIZE_PTR;
> > >
> > > - return kmem_cache_alloc_node(s, flags, node);
> > > + ret = kmem_cache_alloc_node_notrace(s, flags, node);
> > > +
> > > + kmemtrace_mark_alloc_node(KMEMTRACE_TYPE_KMALLOC,
> > > + _THIS_IP_, ret,
> > > + size, s->size, flags, node);
> > > +
> > > + return ret;
> >
> > You could simplify the stuff in slub.h if you would fall back to the uninlined
> > functions in the case that kmemtrace is enabled. IMHO adding additional inline
> > code here does grow these function to a size where inlining is not useful anymore.
>
> So, if CONFIG_KMEMTRACE is enabled, make the inlined version go away
> completely? I'm okay with that though I wonder if that means we now take
> a performance hit when CONFIG_KMEMTRACE is enabled but tracing is
> disabled at run-time...

Oh, good. I'm also thinking to add a macro that expands to simple inline when
CONFIG_KMEMTRACE is disabled and to __always_inline otherwise.

> > > + kmemtrace_mark_alloc(KMEMTRACE_TYPE_CACHE, _RET_IP_, ret,
> > > + s->objsize, s->size, gfpflags);
> > > +
> > > + return ret;
> > > }
> >
> > _RET_IP == __builtin_return_address(0) right? Put that into a local variable?
> > At least we need consistent usage within one function. Maybe convert
> > __builtin_return_address(0) to _RET_IP_ within slub?
>
> I think we should just convert SLUB to use _RET_IP_ everywhere. Eduard,
> care to make a patch and send it and rebase this on top of that?

Sure. Will get back soon.