[Bug 110950] RT cpu starvation due to driver threads or memory access

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=110950

--- Comment #6 from Chris Wilson <chris at chris-wilson.co.uk> ---
Just a quick check on the baseline, the results of our cycletest for measuring
RT thread latency, maximum latency measured during a 120s period:

x baseline-max.lt
+ i915-max.lt
+------------------------------------------------------------------------------+
| xxx       +                                                                 
|
| xxxxx     +  + +                                                            
|
| xxxxx     ++ + *                                                            
|
| xxxxxx    *+ + *                                                            
|
| xxxxxxx   *+ ++*                                                            
|
| xxxxxxx  x*+ ++*                                                            
|
| xxxxxxx  **+x*+*                                                            
|
|xxxxxxxxx **+*****+    +          +              +        +  +         +    +
|
|xxxxxxxxxx**+*****+x+  +    ++    + +  +  ++     +  +    ++  ++ + +    +    +
|
|xxxxxxxxxx**+******x**x*x++++*+  ++ + ++ ++++ + ++  ++  ++++ +++++++++ +   
++|
| |____M_A_____|                                                              
|
|           |___________M_________A____________________|                      
|
+------------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x 120            11            47            18     20.533333     7.7924045
+ 120            23           105            39     50.716667     26.207377

in microseconds. So even in the best case, the worst case impact of submitting
nops is on average 50us.

Now, this does not take into account any impact memory contention has on the RT
thread since we are not stressing the GPU in that manner. Nor does it setup an
isolated cpu. Just establishing expectations for j1900.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the QA Contact for the bug.
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20190620/8d6cc4ba/attachment.html>