On Fri, Jun 26, 2015 at 08:51:58AM +1000, Benjamin Herrenschmidt wrote: > On Thu, 2015-06-25 at 21:40 +0000, Casey Leedom wrote: > > Hhmmm, so what do PowerPC Drivers do when they want to take > > advantage of Write Combining? Do their own Endian Swizzling > > with the __raw_*() APIs? > > Yeah either, we need to fix our relaxed implementation (patch > welcome :-) Yikes, so although powerpc has useful heuristics to automatically enable WC the default write ops have been nullifying its effects? Shouldn't this have been blatantly obvious in performance benchmarks and expectations? If not a change should give considerable performance gains... If the WC was nullified on powerpc then the experience and value of the heuristics have less value and even if they are going to be only considered for userspace mmap() it should be taken with a bit grain of salt it seems. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
