[Intel-gfx] [PATCH 8/8] drm/i915: Expose RPCS (SSEU) configuration to userspace

[Rogozhkin, Dmitry V]

>> I'm pretty sure Dmitry wants dynamic configurations.

Yes, I afraid we really need dynamic slice configurations for media.

From: Landwerlin, Lionel G
Sent: Friday, May 4, 2018 9:25 AM
To: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>; intel-gfx at lists.freedesktop.org; Rogozhkin, Dmitry V <dmitry.v.rogozhkin at intel.com>
Subject: Re: [Intel-gfx] [PATCH 8/8] drm/i915: Expose RPCS (SSEU) configuration to userspace

On 03/05/18 18:18, Tvrtko Ursulin wrote:
  +int intel_lr_context_set_sseu(struct i915_gem_context *ctx,
+                  struct intel_engine_cs *engine,
+                  struct i915_gem_context_sseu *sseu)
+{
+    struct drm_i915_private *dev_priv = ctx->i915;
+    struct intel_context *ce;
+    enum intel_engine_id id;
+    int ret;
+
+    lockdep_assert_held(&dev_priv->drm.struct_mutex);
+
+    if (memcmp(sseu, &ctx->engine[engine->id].sseu, sizeof(*sseu)) == 0)
+        return 0;
+
+    /*
+     * We can only program this on render ring.
+     */
+    ce = &ctx->engine[RCS];
+
+    if (ce->pin_count) { /* Assume that the context is active! */
+        ret = i915_gem_switch_to_kernel_context(dev_priv);
+        if (ret)
+            return ret;
+
+        ret = i915_gem_wait_for_idle(dev_priv,
+                         I915_WAIT_INTERRUPTIBLE |
+                         I915_WAIT_LOCKED);

Could we consider the alternative of only allowing this to be configured on context create? That way we would not need to idle the GPU every time userspace decides to fiddle with it. It is unprivileged so quite an easy way for random app to ruin GPU performance for everyone.

Regards,

Tvrtko


I'm pretty sure Dmitry wants dynamic configurations.

Dmitry?
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