On Fri, Mar 07, 2014 at 09:39:44AM +0100, Daniel Vetter wrote: > On Fri, Mar 07, 2014 at 08:30:37AM +0000, Chris Wilson wrote: > > We don't always want to write into main memory with pwrite. The shmem > > fast path in particular is used for memory that is cacheable - under > > such circumstances forcing the cache eviction is undesirable. As we will > > always flush the cache when targeting incoherent buffers, we can rely on > > that second pass to apply the cache coherency rules and so benefit from > > in-cache copies otherwise. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Do you have some numbers on this? Looks good otherwise. Comparative figures with 1333MHz DDR3 on crw: 0: Time to snooped copy 16384 bytes x 131072: 19.520µs, 839.4MiB/s 1: Time to snooped copy 16384 bytes x 131072: 19.444µs, 842.6MiB/s 2: Time to snooped copy 16384 bytes x 131072: 18.808µs, 871.1MiB/s Oddly enough though, it was the removing the page flag accesses that made the most impact at a higher level. It will take a while longer to complete checks on pnv. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
