drm/i915: Reduce memory pressure during shrinker by preallocating swizzle pages

On a machine with bit17 swizzling, we need to store the bit17 of the
physical page address in put-pages. This requires a memory allocation,
on average less than a page, which may be difficult to satisfy is the
request to put-pages is on behalf of the shrinker. We could allow that
allocation to pull from the reserved memory pools, but it seems much
safer to preallocate the array for tiled objects on affected machines.

v2: Export i915_gem_object_needs_bit17_swizzle() for reuse.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e9ac3603fbdb226fc8628496b403e96abc79dd4a..2ab476df1dc20bdb62a540f8267a0ca10a64b981 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -30,6 +30,8 @@
 #ifndef _I915_DRV_H_
 #define _I915_DRV_H_
 
+#include <uapi/drm/i915_drm.h>
+
 #include "i915_reg.h"
 #include "intel_bios.h"
 #include "intel_ringbuffer.h"
@@ -1614,6 +1616,14 @@ i915_gem_object_create_stolen(struct drm_device *dev, u32 size);
 void i915_gem_object_release_stolen(struct drm_i915_gem_object *obj);
 
 /* i915_gem_tiling.c */
+inline static bool i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
+{
+       drm_i915_private_t *dev_priv = obj->base.dev->dev_private;
+
+       return dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_9_10_17 &&
+               obj->tiling_mode != I915_TILING_NONE;
+}
+
 void i915_gem_detect_bit_6_swizzle(struct drm_device *dev);
 void i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj);
 void i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj);

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 02d315164aa94e5a462f5416be94d7bc1c54c93e..e4b233df576fe4de89ff793940b4c0330859df60 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -271,14 +271,6 @@ i915_gem_create_ioctl(struct drm_device *dev, void *data,
                               args->size, &args->handle);
 }
 
-static int i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
-{
-       drm_i915_private_t *dev_priv = obj->base.dev->dev_private;
-
-       return dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_9_10_17 &&
-               obj->tiling_mode != I915_TILING_NONE;
-}
-
 static inline int
 __copy_to_user_swizzled(char __user *cpu_vaddr,
                        const char *gpu_vaddr, int gpu_offset,

diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index cedbfd7b3dfab10e915fe23ea3fc43afc661c302..65f1d4f3f77586f43e397a360add22363dd97c9c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -396,6 +396,18 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
        /* we have to maintain this existing ABI... */
        args->stride = obj->stride;
        args->tiling_mode = obj->tiling_mode;
+
+       /* Try to preallocate memory required to save swizzling on put-pages */
+       if (i915_gem_object_needs_bit17_swizzle(obj)) {
+               if (obj->bit_17 == NULL) {
+                       obj->bit_17 = kmalloc(BITS_TO_LONGS(obj->base.size >> PAGE_SHIFT) *
+                                             sizeof(long), GFP_KERNEL);
+               }
+       } else {
+               kfree(obj->bit_17);
+               obj->bit_17 = NULL;
+       }
+
        drm_gem_object_unreference(&obj->base);
        mutex_unlock(&dev->struct_mutex);