| Message ID | 1347620267-11275-2-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Fri, 14 Sep 2012 11:57:47 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote: > v2: Limit the WC mapping to older generations as we should the TLB > invalidation on SandyBridge+ unreliable. /me fires his editor and proof-reader v2: Limit the WC mapping to older generations as we have observed that the TLB invalidation on SandyBridge+ is unreliable with WC updates. See i-g-t/tests/gem_gtt_cpu_tlb -Chris
diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c index 258873a..8b0f6d19 100644 --- a/drivers/char/agp/intel-gtt.c +++ b/drivers/char/agp/intel-gtt.c @@ -666,9 +666,14 @@ static int intel_gtt_init(void) gtt_map_size = intel_private.base.gtt_total_entries * 4; - intel_private.gtt = ioremap(intel_private.gtt_bus_addr, - gtt_map_size); - if (!intel_private.gtt) { + intel_private.gtt = NULL; + if (INTEL_GTT_GEN < 6) + intel_private.gtt = ioremap_wc(intel_private.gtt_bus_addr, + gtt_map_size); + if (intel_private.gtt == NULL) + intel_private.gtt = ioremap(intel_private.gtt_bus_addr, + gtt_map_size); + if (intel_private.gtt == NULL) { intel_private.driver->cleanup(); iounmap(intel_private.registers); return -ENOMEM;
Rewriting the PTE entries using an WC mapping is roughly an order of magnitude faster than through the uncached mapping. This makes an observable difference on workloads that cycle through large numbers of buffers, for example Chromium using ShmPixmaps where virtually all the CPU time is currently spent rebinding the userptr. v2: Limit the WC mapping to older generations as we should the TLB invalidation on SandyBridge+ unreliable. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/char/agp/intel-gtt.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)