Re: [Pcihpd-discuss] [PATCH 2/5] Construct one fakephp slot per pci slot

Alex Chiang
2007-11-14T15:12:38Z

Hi Eike,

* Rolf Eike Beer <eike-hotplug@sf-tec.de>:
> Am Mittwoch, 14. November 2007 schrieb Alex Chiang:
> > * Rolf Eike Beer <eike-hotplug@sf-tec.de>:
> > >
> > > This is ugly. Please do it the way we already do e.g. for
> > > acpiphp: add a char[8] to "struct dummy_slot" and just
> > > reference that here.
> >
> > I took at look at the code in acpiphp you're talking about,
> > and I'm not sure why you think the above is "ugly". We're
> > talking about a runtime vs compile time storage for the name,
> > and doing a kmalloc/sprintf is a pretty standard idiom.
> >
> > BTW, I did incorporate both Linas' and Willy's comments, by
> > changing the kmalloc size to an explicit 32, and using
> > snprintf instead.
> >
> > In any case, for your particular comment, I think I'm going
> > to leave it alone for now, and let Greg weigh in with the
> > final recommendation.
>
> Because we have another allocation of very small size for every
> slot here.
>
> struct dummy_slot has a size of 4 pointers, that's 16 byte for
> 32 bit architectures. Putting 8 byte of additional storage here
> would save a complete allocation on 32 bit platforms. For 64
> bit platforms the memory usage is the same but we do less
> allocations (i.e. less points to fail) and less memory
> fragmentation.
>
> Btw: your code lacks a check if kmalloc() returns NULL.

Good points. I'll make your suggested change for v2.

Thanks.

/ac