On Thu, Apr 26, 2018 at 11:20:44AM +0200, Daniel Vetter wrote: > The above is already what we're implementing in i915, at least > conceptually (it all boils down to clflush instructions because those > both invalidate and flush). The clwb instruction that just writes back dirty cache lines might be very interesting for the x86 non-coherent dma case. A lot of architectures use their equivalent to prepare to to device transfers. > One architectural guarantee we're exploiting is that prefetched (and > hence non-dirty) cachelines will never get written back, but dropped > instead. And to make this work you'll need exactly this guarantee.
