On Mon, Jan 14, 2013 at 8:21 PM, Imre Deak <imre.deak at intel.com> wrote: >> + drm_clflush_virt_range(vaddr + page_offset, 4); >> + *(uint32_t *)(vaddr + page_offset) = reloc->delta; >> + drm_clflush_virt_range(vaddr + page_offset, 4); > > Discussed this already to some degree with Chris, but I still think the > first cache flush is redundant. Nope, since it's a partial cacheline write, we need to first flush out any stale data, then write the dword (which loads the latest data from memory into a cacheline). Then we need to flush the updated cacheline out into main memory again. Iirc I've mentioned this somewhere in the part 4 of my gem intro. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
