Mesa (master): i965: Embrace "unlimited" GTT mmap support
Chris Wilson
ickle at kemper.freedesktop.org
Fri Aug 26 08:12:00 UTC 2016
Module: Mesa
Branch: master
Commit: f92a87a14068dd17a32b41b1586421cef6eaa37f
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=f92a87a14068dd17a32b41b1586421cef6eaa37f
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Wed Aug 24 20:35:46 2016 +0100
i965: Embrace "unlimited" GTT mmap support
>From about kernel 4.9, GTT mmaps are virtually unlimited. A new
parameter, I915_PARAM_MMAP_GTT_VERSION, is added to advertise the
feature so query it and use it to avoid limiting tiled allocations to
only fit within the mappable aperture.
A couple of caveats:
- fence support is still limited by stride to 262144 and the stride
needs to be a multiple of tile_width (as before, and same limitation as
the current 3D pipeline in hardware)
- the max_gtt_map_object_size forcing untiled may be hiding a few bugs
in handling of large objects, though none were spotted in piglits.
See kernel commit 4cc6907501ed ("drm/i915: Add I915_PARAM_MMAP_GTT_VERSION
to advertise unlimited mmaps").
v2: Include some commentary on mmap virtual space vs CPU addressable
space.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
src/mesa/drivers/dri/i965/brw_context.c | 17 ++---------
src/mesa/drivers/dri/i965/brw_context.h | 2 +-
src/mesa/drivers/dri/i965/intel_screen.c | 48 ++++++++++++++++++++++++++++++++
src/mesa/drivers/dri/i965/intel_screen.h | 2 ++
4 files changed, 53 insertions(+), 16 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index d6f0d7b..1364393 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -1044,21 +1044,6 @@ brwCreateContext(gl_api api,
brw->urb.max_ds_entries = devinfo->urb.max_ds_entries;
brw->urb.max_gs_entries = devinfo->urb.max_gs_entries;
- /* Estimate the size of the mappable aperture into the GTT. There's an
- * ioctl to get the whole GTT size, but not one to get the mappable subset.
- * It turns out it's basically always 256MB, though some ancient hardware
- * was smaller.
- */
- uint32_t gtt_size = 256 * 1024 * 1024;
-
- /* We don't want to map two objects such that a memcpy between them would
- * just fault one mapping in and then the other over and over forever. So
- * we would need to divide the GTT size by 2. Additionally, some GTT is
- * taken up by things like the framebuffer and the ringbuffer and such, so
- * be more conservative.
- */
- brw->max_gtt_map_object_size = gtt_size / 4;
-
if (brw->gen == 6)
brw->urb.gs_present = false;
@@ -1069,6 +1054,8 @@ brwCreateContext(gl_api api,
brw->predicate.state = BRW_PREDICATE_STATE_RENDER;
+ brw->max_gtt_map_object_size = screen->max_gtt_map_object_size;
+
brw->use_resource_streamer = screen->has_resource_streamer &&
(env_var_as_boolean("INTEL_USE_HW_BT", false) ||
env_var_as_boolean("INTEL_USE_GATHER", false));
diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index e0f7000..1a4efa3 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -853,7 +853,7 @@ struct brw_context
*/
bool perf_debug;
- uint32_t max_gtt_map_object_size;
+ uint64_t max_gtt_map_object_size;
int gen;
int gt;
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 7876652..cb007d7 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -995,6 +995,17 @@ intel_get_boolean(struct intel_screen *screen, int param)
return (intel_get_param(screen, param, &value) == 0) && value;
}
+static int
+intel_get_integer(struct intel_screen *screen, int param)
+{
+ int value = -1;
+
+ if (intel_get_param(screen, param, &value) == 0)
+ return value;
+
+ return -1;
+}
+
static void
intelDestroyScreen(__DRIscreen * sPriv)
{
@@ -1565,6 +1576,43 @@ __DRIconfig **intelInitScreen2(__DRIscreen *psp)
if (INTEL_DEBUG & DEBUG_AUB)
drm_intel_bufmgr_gem_set_aub_dump(intelScreen->bufmgr, true);
+#ifndef I915_PARAM_MMAP_GTT_VERSION
+#define I915_PARAM_MMAP_GTT_VERSION 40 /* XXX delete me with new libdrm */
+#endif
+ if (intel_get_integer(intelScreen, I915_PARAM_MMAP_GTT_VERSION) >= 1) {
+ /* Theorectically unlimited! At least for individual objects...
+ *
+ * Currently the entire (global) address space for all GTT maps is
+ * limited to 64bits. That is all objects on the system that are
+ * setup for GTT mmapping must fit within 64bits. An attempt to use
+ * one that exceeds the limit with fail in drm_intel_bo_map_gtt().
+ *
+ * Long before we hit that limit, we will be practically limited by
+ * that any single object must fit in physical memory (RAM). The upper
+ * limit on the CPU's address space is currently 48bits (Skylake), of
+ * which only 39bits can be physical memory. (The GPU itself also has
+ * a 48bit addressable virtual space.) We can fit over 32 million
+ * objects of the current maximum allocable size before running out
+ * of mmap space.
+ */
+ intelScreen->max_gtt_map_object_size = UINT64_MAX;
+ } else {
+ /* Estimate the size of the mappable aperture into the GTT. There's an
+ * ioctl to get the whole GTT size, but not one to get the mappable subset.
+ * It turns out it's basically always 256MB, though some ancient hardware
+ * was smaller.
+ */
+ uint32_t gtt_size = 256 * 1024 * 1024;
+
+ /* We don't want to map two objects such that a memcpy between them would
+ * just fault one mapping in and then the other over and over forever. So
+ * we would need to divide the GTT size by 2. Additionally, some GTT is
+ * taken up by things like the framebuffer and the ringbuffer and such, so
+ * be more conservative.
+ */
+ intelScreen->max_gtt_map_object_size = gtt_size / 4;
+ }
+
intelScreen->hw_has_swizzling = intel_detect_swizzling(intelScreen);
intelScreen->hw_has_timestamp = intel_detect_timestamp(intelScreen);
diff --git a/src/mesa/drivers/dri/i965/intel_screen.h b/src/mesa/drivers/dri/i965/intel_screen.h
index 98f9d24..f62b39f 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.h
+++ b/src/mesa/drivers/dri/i965/intel_screen.h
@@ -44,6 +44,8 @@ struct intel_screen
__DRIscreen *driScrnPriv;
+ uint64_t max_gtt_map_object_size;
+
bool no_hw;
bool hw_has_swizzling;
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