perf(linux): AM62X: Update PREEMPT_RT perf numbers for 11.1

Update the real-time Linux latency numbers for SDK 11.1

Signed-off-by: Bryan Brattlof <[email protected]>

Author: bryanbrattlof

source/devices/AM62X/linux/RT_Linux_Performance_Guide.rst

@@ -61,13 +61,22 @@ Test commands used for running stress-ng and cyclictest together
    stress-ng --cpu-method=all -c 4 &
    cyclictest -m -Sp80 -D6h -h400 -i200 -M -q
 
-The latencies observed with this SDK are summarized below:
+The latencies observed with the default yocto SDK image on
+https://www.ti.com/tool/SK-AM62B-P1 are summarized below:
+
+.. note::
+
+   A known issue in this SDK release is affecting this benchmark.
+   Applying `this patch`_ on Yocto's meta-ti layer will restore the
+   context switch latencies to the values you see below.
 
 .. csv-table::
    :header: "Latencies","CPU 0","CPU 1","CPU 2","CPU 3"
 
-   "Minimum (usec)","5","5","4","4"
-   "Average (usec)","7","5","6","6"
-   "Maximum (usec)","66","41","73","70"
+   "Minimum (usec)","5","5","5","5"
+   "Average (usec)","6","6","6","6"
+   "Maximum (usec)","62","46","47","52"
 
 .. image:: img/rt-cpu-method-all-latency-histogram.png
+
+.. _this patch: https://lists.yoctoproject.org/g/meta-ti/message/19089