On Fri, 2016-04-22 at 10:09 -0600, Jason Gunthorpe wrote: > On Fri, Apr 22, 2016 at 08:47:56AM +1000, Benjamin Herrenschmidt > wrote: > > > > On Wed, 2016-04-20 at 03:58 -0400, Aneesh Kumar K.V wrote: > > > > > > The driver was requesting for a writethrough mapping. But with > > > thoses > > > flags we will end up with a SAO mapping because we now have > > > memory > > > conherence always enabled. ie, the existing mapping will end up > > > with > > > a WIMG value 0b1110 which is Strong Access Order. > > > > > > Update this to use cache inhibitted guarded mapping > > Why guarded ? If it's performance sensitive (and the driver has > > appropriate barriers where needed), you will get write combining > > without guarded, you won't with it. > This driver uses uncached write combining on x86
Right so if you want something similar on power, use the _wc variant, and make sure you have the appropriate barriers when you need to break combining. Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
