There are cases where a system integrator may wish to raise/lower the
priority of GPU workloads being submitted by specific OS process(es),
independently of how the software self-classifies its own priority.
Exposing "priority offset" as an i915-specific cgroup parameter will
enable such system-level configuration.
Normally GPU contexts start with a priority value of 0
(I915_CONTEXT_DEFAULT_PRIORITY) and then may be adjusted up/down from
there via other mechanisms. We'd like to provide a system-level input
to the priority decision that will be taken into consideration, even
when userspace later attempts to set an absolute priority value via
I915_CONTEXT_PARAM_PRIORITY. The priority offset introduced here
provides a base value that will always be added to (or subtracted from)
the software's self-assigned priority value.
This patch makes priority offset a cgroup-specific value; contexts will
be created with a priority offset based on the cgroup membership of the
process creating the context at the time the context is created. Note
that priority offset is assigned at context creation time; migrating a
process to a different cgroup or changing the offset associated with a
cgroup will only affect new context creation and will not alter the
behavior of existing contexts previously created by the process.
v2:
- Rebase onto new cgroup_priv API
- Use current instead of drm_file->pid to determine which process to
lookup priority for. (Chris)
- Don't forget to subtract priority offset in context_getparam ioctl to
make it match setparam behavior. (Chris)
v3:
- Rebase again onto new idr/kref-based cgroup_priv API
- Bound priority offset such that effective priority from settings
on context + cgroup fall within [-0x7fffff, 0x7fffff]. (Chris)
v4:
- checkpatch warning fixes (Intel CI)
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_cgroup.c | 54 +++++++++++++++++++++++++++++++--
drivers/gpu/drm/i915/i915_drv.h | 7 +++++
drivers/gpu/drm/i915/i915_gem_context.c | 7 +++--
drivers/gpu/drm/i915/i915_gem_context.h | 9 ++++++
drivers/gpu/drm/i915/i915_request.h | 4 +++
include/uapi/drm/i915_drm.h | 1 +
6 files changed, 77 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_cgroup.c b/drivers/gpu/drm/i915/i915_cgroup.c
index efe76c2a8915..0921d624f840 100644
--- a/drivers/gpu/drm/i915/i915_cgroup.c
+++ b/drivers/gpu/drm/i915/i915_cgroup.c
@@ -10,6 +10,8 @@
#include "i915_drv.h"
struct i915_cgroup_data {
+ int priority_offset;
+
struct kref ref;
};
@@ -54,7 +56,6 @@ i915_cgroup_shutdown(struct drm_i915_private *dev_priv)
* Return i915 cgroup private data, creating and registering it if one doesn't
* already exist for this cgroup.
*/
-__maybe_unused
static struct i915_cgroup_data *
get_or_create_cgroup_data(struct drm_i915_private *dev_priv,
struct cgroup *cgrp)
@@ -98,9 +99,11 @@ i915_cgroup_setparam_ioctl(struct drm_device *dev,
void *data,
struct drm_file *file)
{
+ struct drm_i915_private *dev_priv = to_i915(dev);
struct drm_i915_cgroup_param *req = data;
struct cgroup *cgrp;
- int ret;
+ struct i915_cgroup_data *cgrpdata;
+ int top, bot, ret = 0;
/* We don't actually support any flags yet. */
if (req->flags) {
@@ -127,14 +130,61 @@ i915_cgroup_setparam_ioctl(struct drm_device *dev,
goto out;
}
+ cgrpdata = get_or_create_cgroup_data(dev_priv, cgrp);
+ if (IS_ERR(cgrpdata)) {
+ ret = PTR_ERR(cgrpdata);
+ goto out;
+ }
+
switch (req->param) {
+ case I915_CGROUP_PARAM_PRIORITY_OFFSET:
+ top = req->value + I915_CONTEXT_MAX_USER_PRIORITY;
+ bot = req->value - I915_CONTEXT_MIN_USER_PRIORITY;
+ if (top <= I915_PRIORITY_MAX && bot >= I915_PRIORITY_MIN) {
+ DRM_DEBUG_DRIVER("Setting cgroup priority offset to %lld\n",
+ req->value);
+ cgrpdata->priority_offset = req->value;
+ } else {
+ DRM_DEBUG_DRIVER("Invalid cgroup priority offset %lld\n",
+ req->value);
+ ret = -EINVAL;
+ }
+ break;
+
default:
DRM_DEBUG_DRIVER("Invalid cgroup parameter %lld\n", req->param);
ret = -EINVAL;
}
+ kref_put(&cgrpdata->ref, i915_cgroup_free);
+
out:
cgroup_put(cgrp);
return ret;
}
+
+/*
+ * Generator for simple getter functions that look up a cgroup private data
+ * field for the current task's cgroup. It's safe to call these before
+ * a cgroup private data key has been registered; they'll just return the
+ * default value in that case.
+ */
+#define CGROUP_GET(name, field, def) \
+int i915_cgroup_get_current_##name(struct drm_i915_private *dev_priv) \
+{ \
+ struct kref *ref; \
+ int val = def; \
+ if (!dev_priv->cgroup_priv_key) \
+ return def; \
+ ref = cgroup_priv_get_current(dev_priv->cgroup_priv_key); \
+ if (ref) { \
+ val = cgrp_ref_to_i915(ref)->field; \
+ kref_put(ref, i915_cgroup_free); \
+ } \
+ return val; \
+}
+
+CGROUP_GET(prio_offset, priority_offset, 0)
+
+#undef CGROUP_GET
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ed365fae1073..72e6cd7bfbae 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2693,6 +2693,7 @@ int i915_cgroup_init(struct drm_i915_private *dev_priv);
int i915_cgroup_setparam_ioctl(struct drm_device *dev, void *data,
struct drm_file *file);
void i915_cgroup_shutdown(struct drm_i915_private *dev_priv);
+int i915_cgroup_get_current_prio_offset(struct drm_i915_private *dev_priv);
#else
static inline int
i915_cgroup_init(struct drm_i915_private *dev_priv)
@@ -2708,6 +2709,12 @@ i915_cgroup_setparam_ioctl(struct drm_device *dev, void *data,
{
return -EINVAL;
}
+
+static inline int
+i915_cgroup_get_current_prio_offset(struct drm_i915_private *dev_priv)
+{
+ return 0;
+}
#endif
/* i915_drv.c */
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 4bae1be52294..f9b6fe0fd3ee 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -280,7 +280,8 @@ __create_hw_context(struct drm_i915_private *dev_priv,
kref_init(&ctx->ref);
list_add_tail(&ctx->link, &dev_priv->contexts.list);
ctx->i915 = dev_priv;
- ctx->priority = I915_PRIORITY_NORMAL;
+ ctx->priority_offset = i915_cgroup_get_current_prio_offset(dev_priv);
+ ctx->priority = I915_PRIORITY_NORMAL + ctx->priority_offset;
INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
INIT_LIST_HEAD(&ctx->handles_list);
@@ -748,7 +749,7 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
args->value = i915_gem_context_is_bannable(ctx);
break;
case I915_CONTEXT_PARAM_PRIORITY:
- args->value = ctx->priority;
+ args->value = ctx->priority - ctx->priority_offset;
break;
default:
ret = -EINVAL;
@@ -821,7 +822,7 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
!capable(CAP_SYS_NICE))
ret = -EPERM;
else
- ctx->priority = priority;
+ ctx->priority = priority + ctx->priority_offset;
}
break;
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index 7854262ddfd9..c3b4fb54fbb6 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -150,6 +150,15 @@ struct i915_gem_context {
*/
int priority;
+ /**
+ * @priority_offset: priority offset
+ *
+ * A value, configured via cgroup, that sets the starting priority
+ * of the context. Any priority set explicitly via context parameter
+ * will be added to the priority offset.
+ */
+ int priority_offset;
+
/** ggtt_offset_bias: placement restriction for context objects */
u32 ggtt_offset_bias;
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 72b13fc2b72b..cf7a7147daf3 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -87,6 +87,10 @@ enum {
I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY,
I915_PRIORITY_DEFAULT_DISPBOOST = I915_CONTEXT_MAX_USER_PRIORITY + 1,
+ /* Range reachable by combining user priority + cgroup offset */
+ I915_PRIORITY_MAX = 0x7fffff,
+ I915_PRIORITY_MIN = -I915_PRIORITY_MAX,
+
/* Special case priority values */
I915_PRIORITY_INVALID = INT_MIN,
I915_PRIORITY_IDLE = INT_MIN + 1,
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 735128fa61de..6b70f46d224e 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1726,6 +1726,7 @@ struct drm_i915_cgroup_param {
__s32 cgroup_fd;
__u32 flags;
__u64 param;
+#define I915_CGROUP_PARAM_PRIORITY_OFFSET 0x1
__s64 value;
};
--
2.14.3
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