Re: [PATCH] [RFC] slub tracing: move trace calls out of always inlined functions to reduce kernel code size

Richard Kennedy
2010-10-14T09:49:35Z

On Thu, 2010-10-14 at 10:09 +0300, Pekka Enberg wrote:
> On 10/13/10 7:09 PM, Richard Kennedy wrote:
> > Having the trace calls defined in the always inlined kmalloc functions
> > in include/linux/slub_def.h causes a lot of code duplication as the
> > trace functions get instantiated for each kamalloc call site. This can
> > simply be removed by pushing the trace calls down into the functions in
> > slub.c.
> >
> > On my x86_64 built this patch shrinks the code size of the kernel by
> > approx 29K and also shrinks the code size of many modules -- too many to
> > list here ;)
> >
> > size vmlinux.o reports
> > text data bss dec hex filename
> > 4777011 602052 763072 6142135 5db8b7 vmlinux.o
> > 4747120 602388 763072 6112580 5d4544 vmlinux.o.patch
>
> Impressive kernel text savings!
>
> > index 13fffe1..32b89ee 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > +void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
> > +{
> > + void *ret = (void *) __get_free_pages(flags | __GFP_COMP, order);
> > +
> > + kmemleak_alloc(ret, size, 1, flags);
> > + trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE<< order, flags);
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(kmalloc_order);
> > +
> This doesn't make sense to be out-of-line for the !CONFIG_TRACE case.
> I'd just wrap that with "#ifdef CONFIG_TRACE" and put an inline version
> in the header for !TRACE.
>
> Pekka

Yes, OK I'll do that.
regards
Richard