[PATCH 1/2] drm/i915: use correct node for handling cache domain eviction

[PATCH 1/2] drm/i915: use correct node for handling cache domain eviction

[Matthew Auld]

It looks like we were incorrectly comparing vma->node against itself
instead of the target node, when evicting for a node on systems where we
need guard pages between regions with different cache domains. As a
consequence we can end up trying to needlessly evict neighbouring nodes,
even if they have the same cache domain, and if they were pinned we
would fail the eviction.

Fixes: 625d988acc28 ("drm/i915: Extract reserving space in the GTT to a helper")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem_evict.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
index a0de5734f7d0..2da3a94fc9f3 100644
--- a/drivers/gpu/drm/i915/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/i915_gem_evict.c
@@ -299,12 +299,12 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
 		 * those as well to make room for our guard pages.
 		 */
 		if (check_color) {
-			if (vma->node.start + vma->node.size == node->start) {
-				if (vma->node.color == node->color)
+			if (node->start + node->size == target->start) {
+				if (node->color == target->color)
 					continue;
 			}
-			if (vma->node.start == node->start + node->size) {
-				if (vma->node.color == node->color)
+			if (node->start == target->start + target->size) {
+				if (node->color == target->color)
 					continue;
 			}
 		}
-- 
2.9.3

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[PATCH 2/2] drm/i915/selftests: exercise cache domain eviction

[Matthew Auld]

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
---
 drivers/gpu/drm/i915/selftests/i915_gem_evict.c | 80 +++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_evict.c b/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
index 97af353db218..e92c235d0200 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
@@ -202,6 +202,85 @@ static int igt_evict_for_vma(void *arg)
 	return err;
 }
 
+static void mock_color_adjust(const struct drm_mm_node *node,
+			      unsigned long color,
+			      u64 *start,
+			      u64 *end)
+{
+}
+
+static int igt_evict_for_cache_color(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct i915_ggtt *ggtt = &i915->ggtt;
+	const unsigned long flags = PIN_OFFSET_FIXED;
+	struct drm_mm_node target = {
+		.start = I915_GTT_PAGE_SIZE * 2,
+		.size = I915_GTT_PAGE_SIZE,
+		.color = I915_CACHE_LLC,
+	};
+	struct drm_i915_gem_object *obj;
+	struct i915_vma *vma;
+	int err;
+
+	ggtt->base.mm.color_adjust = mock_color_adjust;
+
+	obj = i915_gem_object_create_internal(i915, I915_GTT_PAGE_SIZE);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto cleanup;
+	}
+	i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
+
+	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
+				       I915_GTT_PAGE_SIZE | flags);
+	if (IS_ERR(vma)) {
+		pr_err("[0]i915_gem_object_ggtt_pin failed\n");
+		err = PTR_ERR(vma);
+		goto cleanup;
+	}
+
+	obj = i915_gem_object_create_internal(i915, I915_GTT_PAGE_SIZE);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto cleanup;
+	}
+	i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
+
+	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
+				       (I915_GTT_PAGE_SIZE * 2) | flags);
+	if (IS_ERR(vma)) {
+		pr_err("[1]i915_gem_object_ggtt_pin failed\n");
+		err = PTR_ERR(vma);
+		goto cleanup;
+	}
+
+	i915_vma_unpin(vma);
+
+	err = i915_gem_evict_for_node(&ggtt->base, &target, 0);
+	if (err) {
+		pr_err("[0]i915_gem_evict_for_node returned err=%d\n", err);
+		goto cleanup;
+	}
+
+	target.color = I915_CACHE_L3_LLC;
+
+	err = i915_gem_evict_for_node(&ggtt->base, &target, 0);
+	if (!err) {
+		pr_err("[1]i915_gem_evict_for_node returned err=%d\n", err);
+		err = -EINVAL;
+		goto cleanup;
+	}
+
+	err = 0;
+
+cleanup:
+	unpin_ggtt(i915);
+	cleanup_objects(i915);
+	ggtt->base.mm.color_adjust = NULL;
+	return err;
+}
+
 static int igt_evict_vm(void *arg)
 {
 	struct drm_i915_private *i915 = arg;
@@ -241,6 +320,7 @@ int i915_gem_evict_mock_selftests(void)
 	static const struct i915_subtest tests[] = {
 		SUBTEST(igt_evict_something),
 		SUBTEST(igt_evict_for_vma),
+		SUBTEST(igt_evict_for_cache_color),
 		SUBTEST(igt_evict_vm),
 		SUBTEST(igt_overcommit),
 	};
-- 
2.9.3

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Re: [PATCH 2/2] drm/i915/selftests: exercise cache domain eviction

[Chris Wilson]

On Fri, Mar 03, 2017 at 06:03:35PM +0000, Matthew Auld wrote:
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> ---
>  drivers/gpu/drm/i915/selftests/i915_gem_evict.c | 80 +++++++++++++++++++++++++
>  1 file changed, 80 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_evict.c b/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
> index 97af353db218..e92c235d0200 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
> @@ -202,6 +202,85 @@ static int igt_evict_for_vma(void *arg)
>  	return err;
>  }
>  
> +static void mock_color_adjust(const struct drm_mm_node *node,
> +			      unsigned long color,
> +			      u64 *start,
> +			      u64 *end)
> +{

Ah. I see, this is because evict_for_node makes the assumption that any
color_adjust is i915_ggtt_color_adjust. I was wondering. Please add a
note here about the magic.

> +}
> +
> +static int igt_evict_for_cache_color(void *arg)
> +{
> +	struct drm_i915_private *i915 = arg;
> +	struct i915_ggtt *ggtt = &i915->ggtt;
> +	const unsigned long flags = PIN_OFFSET_FIXED;
> +	struct drm_mm_node target = {
> +		.start = I915_GTT_PAGE_SIZE * 2,
> +		.size = I915_GTT_PAGE_SIZE,
> +		.color = I915_CACHE_LLC,
> +	};
> +	struct drm_i915_gem_object *obj;
> +	struct i915_vma *vma;
> +	int err;
> +
> +	ggtt->base.mm.color_adjust = mock_color_adjust;
> +
> +	obj = i915_gem_object_create_internal(i915, I915_GTT_PAGE_SIZE);
> +	if (IS_ERR(obj)) {
> +		err = PTR_ERR(obj);
> +		goto cleanup;
> +	}
> +	i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
> +
> +	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
> +				       I915_GTT_PAGE_SIZE | flags);
> +	if (IS_ERR(vma)) {
> +		pr_err("[0]i915_gem_object_ggtt_pin failed\n");
> +		err = PTR_ERR(vma);
> +		goto cleanup;
> +	}
> +
> +	obj = i915_gem_object_create_internal(i915, I915_GTT_PAGE_SIZE);
> +	if (IS_ERR(obj)) {
> +		err = PTR_ERR(obj);
> +		goto cleanup;
> +	}
> +	i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
> +

/* Neighbouring; same colour - should fit */
> +	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
> +				       (I915_GTT_PAGE_SIZE * 2) | flags);
> +	if (IS_ERR(vma)) {
> +		pr_err("[1]i915_gem_object_ggtt_pin failed\n");
> +		err = PTR_ERR(vma);
> +		goto cleanup;
> +	}
> +
> +	i915_vma_unpin(vma);
> +

/* Remove just the second vma */
> +	err = i915_gem_evict_for_node(&ggtt->base, &target, 0);
> +	if (err) {
> +		pr_err("[0]i915_gem_evict_for_node returned err=%d\n", err);
> +		goto cleanup;
> +	}
> +

/* Attempt to remove the first *pinned* vma, by removing the (empty) neighbour */
> +	target.color = I915_CACHE_L3_LLC;
> +
> +	err = i915_gem_evict_for_node(&ggtt->base, &target, 0);
> +	if (!err) {
> +		pr_err("[1]i915_gem_evict_for_node returned err=%d\n", err);
> +		err = -EINVAL;
> +		goto cleanup;

Your pr_err("[]") are as bad as mine ;)

I see what you're testing, looks ok. So just a couple of comments for
the next reader.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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Re: [PATCH 1/2] drm/i915: use correct node for handling cache domain eviction

[Chris Wilson]

On Fri, Mar 03, 2017 at 06:03:34PM +0000, Matthew Auld wrote:
> It looks like we were incorrectly comparing vma->node against itself
> instead of the target node, when evicting for a node on systems where we
> need guard pages between regions with different cache domains. As a
> consequence we can end up trying to needlessly evict neighbouring nodes,
> even if they have the same cache domain, and if they were pinned we
> would fail the eviction.
> 
> Fixes: 625d988acc28 ("drm/i915: Extract reserving space in the GTT to a helper")
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> /o\
-Chris

-- 
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Re: [PATCH 1/2] drm/i915: use correct node for handling cache domain eviction

[Joonas Lahtinen]

On pe, 2017-03-03 at 18:18 +0000, Chris Wilson wrote:
> On Fri, Mar 03, 2017 at 06:03:34PM +0000, Matthew Auld wrote:
> > 
> > It looks like we were incorrectly comparing vma->node against itself
> > instead of the target node, when evicting for a node on systems where we
> > need guard pages between regions with different cache domains. As a
> > consequence we can end up trying to needlessly evict neighbouring nodes,
> > even if they have the same cache domain, and if they were pinned we
> > would fail the eviction.
> > 
> > Fixes: 625d988acc28 ("drm/i915: Extract reserving space in the GTT to a helper")
> > Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> 
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> /o\
> -Chris

Good catch, will merge the series once the comments on patch 2 are
addressed.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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✓ Fi.CI.BAT: success for series starting with [1/2] drm/i915: use correct node for handling cache domain eviction

[Patchwork]

== Series Details ==

Series: series starting with [1/2] drm/i915: use correct node for handling cache domain eviction
URL   : https://patchwork.freedesktop.org/series/20646/
State : success

== Summary ==

Series 20646v1 Series without cover letter
https://patchwork.freedesktop.org/api/1.0/series/20646/revisions/1/mbox/

Test gem_exec_flush:
        Subgroup basic-batch-kernel-default-uc:
                pass       -> FAIL       (fi-snb-2600) fdo#100007

fdo#100007 https://bugs.freedesktop.org/show_bug.cgi?id=100007

fi-bdw-5557u     total:278  pass:267  dwarn:0   dfail:0   fail:0   skip:11 
fi-bsw-n3050     total:278  pass:239  dwarn:0   dfail:0   fail:0   skip:39 
fi-bxt-j4205     total:278  pass:259  dwarn:0   dfail:0   fail:0   skip:19 
fi-bxt-t5700     total:278  pass:258  dwarn:0   dfail:0   fail:0   skip:20 
fi-byt-j1900     total:278  pass:251  dwarn:0   dfail:0   fail:0   skip:27 
fi-byt-n2820     total:278  pass:247  dwarn:0   dfail:0   fail:0   skip:31 
fi-hsw-4770      total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16 
fi-hsw-4770r     total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16 
fi-ilk-650       total:278  pass:228  dwarn:0   dfail:0   fail:0   skip:50 
fi-ivb-3520m     total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18 
fi-ivb-3770      total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18 
fi-kbl-7500u     total:278  pass:259  dwarn:1   dfail:0   fail:0   skip:18 
fi-skl-6260u     total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10 
fi-skl-6700hq    total:278  pass:261  dwarn:0   dfail:0   fail:0   skip:17 
fi-skl-6700k     total:278  pass:256  dwarn:4   dfail:0   fail:0   skip:18 
fi-skl-6770hq    total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10 
fi-snb-2520m     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28 
fi-snb-2600      total:278  pass:248  dwarn:0   dfail:0   fail:1   skip:29 

1d7915e7823628a0d548c6ecc5ad5b9a4ae4a6ff drm-tip: 2017y-03m-03d-15h-54m-06s UTC integration manifest
dcfd30d drm/i915/selftests: exercise cache domain eviction
60905a6 drm/i915: use correct node for handling cache domain eviction

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_4060/
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