On May 19, 2014, at 4:25 PM, Andi Kleen <a...@linux.intel.com> wrote:
> On Mon, May 19, 2014 at 10:00:52PM +0000, Rustad, Mark D wrote: >> On May 16, 2014, at 2:43 PM, Andi Kleen <a...@firstfloor.org> wrote: >> >>> From: Andi Kleen <a...@linux.intel.com> >>> >>> ixgbe_read_reg and ixgbe_write_reg are frequently called and are very big >>> because they have complex error handling code. >> >> Actually, this patch doesn't do anything to ixgbe_write_reg, which would >> almost certainly be very bad for performance, but instead changes >> ixgbe_write_reg64. > > I doubt a few cycles around the write make a lot of difference for MMIO. MMIO > is dominated > by other things. > >> The latter is not in a performance-sensitive path, but is only called from >> one site, so there is little reason to take it out-of-line. > > True I moved the wrong one. > > ixgbe_write_reg 3305 (0.00%) 8 409 > > >> I already have a patch in queue to make ixgbe_read_reg out-of-line, because >> it does have a very costly memory footprint inline, as you have found. > > Please move write_reg too. I will take a look at moving most of them out-of-line. There are just a few in very hot paths that should remain inline. -- Mark Rustad, Networking Division, Intel Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
