PT test: Add 20 PT cases with perf tool.

Signed-off-by: Ammy Yi <ammy.yi@intel.com>

Author: ammyyi

pt/README.md

@@ -1,48 +1,49 @@
 # PT
+
 Intel Processor Trace (Intel PT) is an extension of Intel Architecture that
 captures information about software execution using dedicated hardware facilities
 that cause only minimal performance perturbation to the software being traced.
 
 ## Build Tips
+
 Need prepare intel-pt.h and libipt.so for building PT related cases.
 You can get them in https://github.com/intel/libipt.
 
 ## Usage
+
 Need libipt.so.2 and add it into LD_LIBRARY_PATH before running PT cases.
 You can build libipt.so.2 in https://github.com/intel/libipt.
 
 ```
+# Disable branch and check no TIP/FUP/TNT.
 ./branch
-```
-Disable branch and check no TIP/FUP/TNT.
 
-```
+# User mode trace check
 ./cpl 1
-```
-User mode trace check
-```
+
+# Kernel mode trace check
 ./cpl 2
-```
-Kernel mode trace check
 
-```
+# Check if psb package there.
 ./psb
-```
-Check if psb package there.
 
-```
+# Check reserved bit cannot be set.
 ./negative_test
-```
-Check reserved bit cannot be set.
 
-```
+# Non root user do full trace check.
 ./nonroot_test 1
-```
-Non root user do full trace check.
-```
+
+# Non root user do snapshot trace check.
 ./nonroot_test 2
 ```
-Non root user do snapshot trace check.
 
 ## Expected result
+
 All test results should show pass, no fail.
+Usage for perf_tests.sh:
+
+1. Make sure latest perf is there.
+2. Run case as 
+```
+./perf_tests.sh -t <case name>
+```