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

[Lionel Landwerlin]

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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