--- a/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatGcCauseResults.java	Sat May 19 13:13:09 2018 -0700
+++ b/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatGcCauseResults.java	Sun May 20 20:25:51 2018 +0900
@@ -66,9 +66,6 @@
         int YGC = getIntValue("YGC");
         float YGCT = getFloatValue("YGCT");
         assertThat(YGCT >= 0, "Incorrect time value for YGCT");
-        if (YGC > 0) {
-            assertThat(YGCT > 0, "Number of young generation GC Events is " + YGC + ", but YGCT is 0");
-        }
 
         float GCT = getFloatValue("GCT");
         assertThat(GCT >= 0, "Incorrect time value for GCT");
@@ -86,15 +83,11 @@
         if (CGC > 0) {
             CGCT = getFloatValue("CGCT");
             assertThat(CGCT >= 0, "Incorrect time value for CGCT");
-            assertThat(CGCT > 0, "Number of concurrent GC events is " + CGC + ", but CGCT is 0");
         }
 
         int FGC = getIntValue("FGC");
         float FGCT = getFloatValue("FGCT");
         assertThat(FGCT >= 0, "Incorrect time value for FGCT");
-        if (FGC > 0) {
-            assertThat(FGCT > 0, "Number of full GC events is " + FGC + ", but FGCT is 0");
-        }
 
         assertThat(GCT >= FGCT, "GCT < YGCT (total garbage collection time < full generation garbage collection time)");
 

--- a/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatGcNewResults.java	Sat May 19 13:13:09 2018 -0700
+++ b/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatGcNewResults.java	Sun May 20 20:25:51 2018 +0900
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,8 +25,8 @@
  * Results of running the JstatGcTool ("jstat -gcnew <pid>")
  *
  * Output example:
- * S0C           S1C         S0U    S1U   TT   MTT  DSS      EC                EU       YGC     YGCT
- * 11264.0  11264.0    0.0    0.0      15  15       0.0      67584.0   1351.7      0      0.000
+ * S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT
+ *   0.0 7168.0    0.0 7168.0 15  15 3584.0  62464.0   5120.0     27    0.340
 
  * Output description:
  * S0C     Current survivor space 0 capacity (KB).
@@ -77,10 +77,6 @@
         int YGC = getIntValue("YGC");
         float YGCT = getFloatValue("YGCT");
 
-        if (YGC > 0) {
-            assertThat(YGCT > 0, "Number of young generation GC Events is " + YGC + ", but YGCT is 0");
-        }
-
         int TT = getIntValue("TT");
         int MTT = getIntValue("MTT");
         assertThat(TT <= MTT, "TT > MTT (tenuring threshold > maximum tenuring threshold)");

--- a/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatGcResults.java	Sat May 19 13:13:09 2018 -0700
+++ b/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatGcResults.java	Sun May 20 20:25:51 2018 +0900
@@ -95,9 +95,6 @@
         int YGC = getIntValue("YGC");
         float YGCT = getFloatValue("YGCT");
         assertThat(YGCT >= 0, "Incorrect time value for YGCT");
-        if (YGC > 0) {
-            assertThat(YGCT > 0, "Number of young generation GC Events is " + YGC + ", but YGCT is 0");
-        }
 
         float GCT = getFloatValue("GCT");
         assertThat(GCT >= 0, "Incorrect time value for GCT");
@@ -115,15 +112,11 @@
         if (CGC > 0) {
             CGCT = getFloatValue("CGCT");
             assertThat(CGCT >= 0, "Incorrect time value for CGCT");
-            assertThat(CGCT > 0, "Number of concurrent GC events is " + CGC + ", but CGCT is 0");
         }
 
         int FGC = getIntValue("FGC");
         float FGCT = getFloatValue("FGCT");
         assertThat(FGCT >= 0, "Incorrect time value for FGCT");
-        if (FGC > 0) {
-            assertThat(FGCT > 0, "Number of full GC events is " + FGC + ", but FGCT is 0");
-        }
 
         assertThat(GCT >= FGCT, "GCT < YGCT (total garbage collection time < full generation garbage collection time)");
 

--- a/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatResults.java	Sat May 19 13:13:09 2018 -0700
+++ b/test/hotspot/jtreg/serviceability/tmtools/jstat/utils/JstatResults.java	Sun May 20 20:25:51 2018 +0900
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -109,12 +109,12 @@
      * measurements
      *
      * @param measurement1 -first measurement
-     * @param measurement2 -first measurement
+     * @param measurement2 -second measurement
      */
     public static void assertGCTimeIncreased(JstatResults measurement1, JstatResults measurement2) {
-        assertThat(measurement2.getFloatValue("YGCT") > measurement1.getFloatValue("YGCT"), "YGCT time didn't increase between measurements 1 and 2");
-        assertThat(measurement2.getFloatValue("FGCT") > measurement1.getFloatValue("FGCT"), "FGCT time didn't increase between measurements 1 and 2");
-        assertThat(measurement2.getFloatValue("GCT") > measurement1.getFloatValue("GCT"), "GCT time didn't increase between measurements 1 and 2");
+        assertThat(measurement2.getFloatValue("YGCT") >= measurement1.getFloatValue("YGCT"), "YGCT time rewinded between measurements 1 and 2");
+        assertThat(measurement2.getFloatValue("FGCT") >= measurement1.getFloatValue("FGCT"), "FGCT time rewinded between measurements 1 and 2");
+        assertThat(measurement2.getFloatValue("GCT") >= measurement1.getFloatValue("GCT"), "GCT time rewinded between measurements 1 and 2");
     }
 
     /**