| Message ID | 1404993911-10544-1-git-send-email-linux@rasmusvillemoes.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
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 <linux@rasmusvillemoes.dk> Applied to pci/misc for v3.17, thanks! > --- > include/linux/pci_ids.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h > index 7fa3173..6ed0bb7 100644 > --- a/include/linux/pci_ids.h > +++ b/include/linux/pci_ids.h > @@ -6,6 +6,8 @@ > * Do not add new entries to this file unless the definitions > * are shared between multiple drivers. > */ > +#ifndef _LINUX_PCI_IDS_H > +#define _LINUX_PCI_IDS_H > > /* Device classes and subclasses */ > > @@ -2968,3 +2970,5 @@ > #define PCI_DEVICE_ID_XEN_PLATFORM 0x0001 > > #define PCI_VENDOR_ID_OCZ 0x1b85 > + > +#endif /* _LINUX_PCI_IDS_H */ > -- > 1.9.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Bjorn Helgaas <bhelgaas@google.com> 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 <linux@rasmusvillemoes.dk> > > 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. Rasmus -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, Jul 12, 2014 at 6:09 AM, Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote: > Bjorn Helgaas <bhelgaas@google.com> 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 <linux@rasmusvillemoes.dk> >> >> 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-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h index 7fa3173..6ed0bb7 100644 --- a/include/linux/pci_ids.h +++ b/include/linux/pci_ids.h @@ -6,6 +6,8 @@ * Do not add new entries to this file unless the definitions * are shared between multiple drivers. */ +#ifndef _LINUX_PCI_IDS_H +#define _LINUX_PCI_IDS_H /* Device classes and subclasses */ @@ -2968,3 +2970,5 @@ #define PCI_DEVICE_ID_XEN_PLATFORM 0x0001 #define PCI_VENDOR_ID_OCZ 0x1b85 + +#endif /* _LINUX_PCI_IDS_H */
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 <linux@rasmusvillemoes.dk> --- include/linux/pci_ids.h | 4 ++++ 1 file changed, 4 insertions(+)