drm/i915/perf: Allow dynamic reconfiguration of the OA stream

Introduce a new perf_ioctl command to change the OA configuration of the
active stream. This allows the OA stream to be reconfigured between
batch buffers, giving greater flexibility in sampling. We inject a
request into the OA context to reconfigure the stream asynchronously on
the GPU in between and ordered with execbuffer calls.

Original patch for dynamic reconfiguration by Lionel Landwerlin.

Link: https://gitlab.freedesktop.org/mesa/mesa/merge_requests/932
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191014201404.22468-3-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 109782e..372c91f 100644 (file)
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -2862,6 +2862,40 @@ static void i915_perf_disable_locked(struct i915_perf_stream *stream)
                stream->ops->disable(stream);
 }
 
+static long i915_perf_config_locked(struct i915_perf_stream *stream,
+                                   unsigned long metrics_set)
+{
+       struct i915_oa_config *config;
+       long ret = stream->oa_config->id;
+
+       config = i915_perf_get_oa_config(stream->perf, metrics_set);
+       if (!config)
+               return -EINVAL;
+
+       if (config != stream->oa_config) {
+               int err;
+
+               /*
+                * If OA is bound to a specific context, emit the
+                * reconfiguration inline from that context. The update
+                * will then be ordered with respect to submission on that
+                * context.
+                *
+                * When set globally, we use a low priority kernel context,
+                * so it will effectively take effect when idle.
+                */
+               err = emit_oa_config(stream, oa_context(stream));
+               if (err == 0)
+                       config = xchg(&stream->oa_config, config);
+               else
+                       ret = err;
+       }
+
+       i915_oa_config_put(config);
+
+       return ret;
+}
+
 /**
  * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
  * @stream: An i915 perf stream
@@ -2885,6 +2919,8 @@ static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
        case I915_PERF_IOCTL_DISABLE:
                i915_perf_disable_locked(stream);
                return 0;
+       case I915_PERF_IOCTL_CONFIG:
+               return i915_perf_config_locked(stream, arg);
        }
 
        return -EINVAL;
@@ -4023,7 +4059,15 @@ void i915_perf_fini(struct drm_i915_private *i915)
  */
 int i915_perf_ioctl_version(void)
 {
-       return 1;
+       /*
+        * 1: Initial version
+        *   I915_PERF_IOCTL_ENABLE
+        *   I915_PERF_IOCTL_DISABLE
+        *
+        * 2: Added runtime modification of OA config.
+        *   I915_PERF_IOCTL_CONFIG
+        */
+       return 2;
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 0c7b281..b008ce8 100644 (file)
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1933,6 +1933,19 @@ struct drm_i915_perf_open_param {
 #define I915_PERF_IOCTL_DISABLE        _IO('i', 0x1)
 
 /**
+ * Change metrics_set captured by a stream.
+ *
+ * If the stream is bound to a specific context, the configuration change
+ * will performed inline with that context such that it takes effect before
+ * the next execbuf submission.
+ *
+ * Returns the previously bound metrics set id, or a negative error code.
+ *
+ * This ioctl is available in perf revision 2.
+ */
+#define I915_PERF_IOCTL_CONFIG _IO('i', 0x2)
+
+/**
  * Common to all i915 perf records
  */
 struct drm_i915_perf_record_header {