[RFC 16/17] drm/i915: Expose per-engine client busyness

Tvrtko Ursulin
2017-10-25T15:36:55Z

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

The new file is named 'busy' and contains a list of, one line for each
engine, monotonically increasing nano-second resolution times each
client's jobs were executing on the GPU.

$ cat /sys/class/drm/card0/clients/5/busy
32516602
0
0
0

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.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem.c | 65 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index cc98c643f42b..d74111b397b4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -631,6 +631,7 @@ struct drm_i915_file_private {
struct {
struct device_attribute pid;
struct device_attribute name;
+ struct device_attribute busy;
} attr;
};

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e8a30c1ceb4f..7a0b96c04666 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5251,6 +5251,56 @@ 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 {
+ u64 total[I915_NUM_ENGINES];
+};
+
+static int busy_add(int _id, void *p, void *data)
+{
+ struct i915_gem_context *ctx = p;
+ struct busy_ctx *bc = data;
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+
+ for_each_engine(engine, ctx->i915, id)
+ bc->total[id] += ctx->engine[id].stats.total;
+
+ return 0;
+}
+
+static ssize_t
+show_client_busy(struct device *kdev, struct device_attribute *attr, char *buf)
+{
+ struct drm_i915_file_private *file_priv =
+ container_of(attr, struct drm_i915_file_private, attr.busy);
+ struct drm_i915_private *i915 = file_priv->dev_priv;
+ unsigned int len = PAGE_SIZE;
+ struct busy_ctx bc = { };
+ ssize_t res = 0;
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+ ssize_t 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);
+
+ for_each_engine(engine, i915, id) {
+ ret = snprintf(buf, len, "%llu\n", bc.total[id]);
+ if (ret <= 0)
+ break;
+ res += ret;
+ len -= ret;
+ buf += ret;
+ }
+
+ return res;
+}
+
int
i915_gem_add_client(struct drm_i915_private *i915,
struct drm_i915_file_private *file_priv,
@@ -5291,10 +5341,23 @@ i915_gem_add_client(struct drm_i915_private *i915,
if (ret)
goto err_attr_pid;

+ attr = &file_priv->attr.busy;
+ attr->attr.name = "busy";
+ attr->attr.mode = 0444;
+ attr->show = show_client_busy;
+
+ ret = sysfs_create_file(file_priv->client_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:
+ 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);
@@ -5309,6 +5372,8 @@ i915_gem_add_client(struct drm_i915_private *i915,
void i915_gem_remove_client(struct drm_i915_file_private *file_priv)
{
sysfs_remove_file(file_priv->client_root,
+ (struct attribute *)&file_priv->attr.busy);
+ sysfs_remove_file(file_priv->client_root,
(struct attribute *)&file_priv->attr.pid);
sysfs_remove_file(file_priv->client_root,
(struct attribute *)&file_priv->attr.name);