[RFC 4/5] drm/i915: Expose per-engine client busyness

Tvrtko Ursulin
2018-02-14T18:50:50Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Expose per-client and per-engine busyness under the previously added sysfs
client root.

The new files are one per-engine instance and located under the 'busy'
directory.

Each contains a monotonically increasing nano-second resolution times each
client's jobs were executing on the GPU.

$ cat /sys/class/drm/card0/clients/5/busy/rcs0
32516602

This data can serve as an interface to implement a top like utility for
GPU jobs. For instance I have prototyped a tool in IGT which produces
periodic output like:

neverball[ 6011]: rcs0: 41.01% bcs0: 0.00% vcs0: 0.00% vecs0: 0.00%
Xorg[ 5664]: rcs0: 31.16% bcs0: 0.00% vcs0: 0.00% vecs0: 0.00%
xfwm4[ 5727]: rcs0: 0.00% bcs0: 0.00% vcs0: 0.00% vecs0: 0.00%

This tools can also be extended to use the i915 PMU and show overall engine
busyness, and engine loads using the queue depth metric.

v2: Use intel_context_engine_get_busy_time.
v3: New directory structure.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 8 ++++
drivers/gpu/drm/i915/i915_gem.c | 86 +++++++++++++++++++++++++++++++++++++++--
2 files changed, 91 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 372d13cb2472..d6b2883b42fe 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -315,6 +315,12 @@ struct drm_i915_private;
struct i915_mm_struct;
struct i915_mmu_object;

+struct i915_engine_busy_attribute {
+ struct device_attribute attr;
+ struct drm_i915_file_private *file_priv;
+ struct intel_engine_cs *engine;
+};
+
struct drm_i915_file_private {
struct drm_i915_private *dev_priv;
struct drm_file *file;
@@ -350,10 +356,12 @@ struct drm_i915_file_private {
unsigned int client_pid;
char *client_name;
struct kobject *client_root;
+ struct kobject *busy_root;

struct {
struct device_attribute pid;
struct device_attribute name;
+ struct i915_engine_busy_attribute busy[I915_NUM_ENGINES];
} attr;
};

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 46ac7b3ca348..01298d924524 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5631,6 +5631,45 @@ show_client_pid(struct device *kdev, struct device_attribute *attr, char *buf)
return snprintf(buf, PAGE_SIZE, "%u", file_priv->client_pid);
}

+struct busy_ctx {
+ struct intel_engine_cs *engine;
+ u64 total;
+};
+
+static int busy_add(int _id, void *p, void *data)
+{
+ struct i915_gem_context *ctx = p;
+ struct busy_ctx *bc = data;
+
+ bc->total +=
+ ktime_to_ns(intel_context_engine_get_busy_time(ctx,
+ bc->engine));
+
+ return 0;
+}
+
+static ssize_t
+show_client_busy(struct device *kdev, struct device_attribute *attr, char *buf)
+{
+ struct i915_engine_busy_attribute *i915_attr =
+ container_of(attr, typeof(*i915_attr), attr);
+ struct drm_i915_file_private *file_priv = i915_attr->file_priv;
+ struct intel_engine_cs *engine = i915_attr->engine;
+ struct drm_i915_private *i915 = engine->i915;
+ struct busy_ctx bc = { .engine = engine };
+ int ret;
+
+ ret = i915_mutex_lock_interruptible(&i915->drm);
+ if (ret)
+ return ret;
+
+ idr_for_each(&file_priv->context_idr, busy_add, &bc);
+
+ mutex_unlock(&i915->drm.struct_mutex);
+
+ return snprintf(buf, PAGE_SIZE, "%llu\n", bc.total);
+}
+
int
i915_gem_add_client(struct drm_i915_private *i915,
struct drm_i915_file_private *file_priv,
@@ -5638,15 +5677,17 @@ i915_gem_add_client(struct drm_i915_private *i915,
unsigned int serial)
{
int ret = -ENOMEM;
+ struct intel_engine_cs *engine;
struct device_attribute *attr;
- char id[32];
+ enum intel_engine_id id, id2;
+ char idstr[32];

file_priv->client_name = kstrdup(task->comm, GFP_KERNEL);
if (!file_priv->client_name)
goto err_name;

- snprintf(id, sizeof(id), "%u", serial);
- file_priv->client_root = kobject_create_and_add(id,
+ snprintf(idstr, sizeof(idstr), "%u", serial);
+ file_priv->client_root = kobject_create_and_add(idstr,
i915->clients_root);
if (!file_priv->client_root)
goto err_client;
@@ -5671,10 +5712,41 @@ i915_gem_add_client(struct drm_i915_private *i915,
if (ret)
goto err_attr_pid;

+ file_priv->busy_root = kobject_create_and_add("busy",
+ file_priv->client_root);
+ if (!file_priv->busy_root)
+ goto err_busy_root;
+
+ for_each_engine(engine, i915, id) {
+ file_priv->attr.busy[id].file_priv = file_priv;
+ file_priv->attr.busy[id].engine = engine;
+ attr = &file_priv->attr.busy[id].attr;
+ attr->attr.name = engine->name;
+ attr->attr.mode = 0444;
+ attr->show = show_client_busy;
+
+ ret = sysfs_create_file(file_priv->busy_root,
+ (struct attribute *)attr);
+ if (ret)
+ goto err_attr_busy;
+ }
+
file_priv->client_pid = pid_nr(get_task_pid(task, PIDTYPE_PID));

return 0;

+err_attr_busy:
+ for_each_engine(engine, i915, id2) {
+ if (id2 == id)
+ break;
+
+ sysfs_remove_file(file_priv->busy_root,
+ (struct attribute *)&file_priv->attr.busy[id2]);
+ }
+ kobject_put(file_priv->busy_root);
+err_busy_root:
+ sysfs_remove_file(file_priv->client_root,
+ (struct attribute *)&file_priv->attr.pid);
err_attr_pid:
sysfs_remove_file(file_priv->client_root,
(struct attribute *)&file_priv->attr.name);
@@ -5688,6 +5760,14 @@ i915_gem_add_client(struct drm_i915_private *i915,

void i915_gem_remove_client(struct drm_i915_file_private *file_priv)
{
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+
+ for_each_engine(engine, file_priv->dev_priv, id) {
+ sysfs_remove_file(file_priv->busy_root,
+ (struct attribute *)&file_priv->attr.busy[id]);
+ }
+ kobject_put(file_priv->busy_root);
sysfs_remove_file(file_priv->client_root,
(struct attribute *)&file_priv->attr.pid);
sysfs_remove_file(file_priv->client_root,
--
2.14.1