On Sat, Jul 12, 2014 at 6:09 AM, Rasmus Villemoes <[email protected]> wrote: > Bjorn Helgaas <[email protected]> writes: > >> On Thu, Jul 10, 2014 at 02:05:11PM +0200, Rasmus Villemoes wrote: >>> Adding an include guard frees the preprocessor from reparsing over >>> 2600 #defines in the cases where pci_ids.h is somehow included more >>> than once. This gives a tiny-but-measurable performance improvement >>> when compiling such files. >>> >>> Signed-off-by: Rasmus Villemoes <[email protected]> >> >> Applied to pci/misc for v3.17, thanks! >> > > Great. > > One thing I thought about, but which is likely undoable in practice: > There are only about 800 files which use any of the #defines in > pci_ids.h, but more than 3000 files include pci.h directly or > indirectly. Making those 800 include pci_ids.h directly and removing it > from pci.h could speed up compilation of the other 2200.
Yeah, changing 800 files for a minor build performance improvement doesn't sound like it'd be worth the churn. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
