On Fri, 1 Jul 2011 16:35:07 -0700, Jesse Barnes <[email protected]> wrote: > By default, the GPU will only share a very small portion of the CPU > cache. With this change, both the GPU and CPU will have full access to > the cache, which should help (sometimes a lot) in most cases.
Joy, this looks to be at best a mixed blessing. For CPU bound games like padman, it degrades performance by about 5% on my desktop SNB. But for nexuiz, there appears to be little change. The ddx shows further regression of the order of 10%. The immediate suspect is that it hurts the use of pixman for trapezoid mask generation, which whilst being less than ideal behaviour and will be fixed in the near future, is indicative of the sort of negative impact this change will have on CPU-memory bound applications. Conversely the equivalent spans-based code is about the only example I found that is sped up by the patch, by about 3%. Having just checked up on 0x900c, I'm even more confused. From my old specs, the register is SNPCR, the snoop control register, which makes more sense than MBC, and that 0<<21 is for the maximum uncore resources, the default setting and the default on my SNB, with 1<<21 being the medium setting. Now, the only reference I have is the register dump with no explanation of what the resource that is actually being controlled... -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
