gc.g1.plab.TestPLABPromotion fails on Linux x86

On Linux x86, gc.g1.plab.TestPLABPromotion fails for me on many submit tests.

Eg:
https://github.com/tstuefe/jdk/runs/1562960505
https://github.com/tstuefe/jdk/runs/1561833114
https://github.com/tstuefe/jdk/runs/1549560140

Also happens to others:
https://github.com/stuart-marks/jdk/runs/1561547066

Test fails with:

STDERR:
java.lang.RuntimeException: Expect that Survivor PLAB allocation are similar to all mem consumed
at gc.g1.plab.TestPLABPromotion.checkLiveObjectsPromotion(TestPLABPromotion.java:188)
at gc.g1.plab.TestPLABPromotion.checkResults(TestPLABPromotion.java:156)
at gc.g1.plab.TestPLABPromotion.main(TestPLABPromotion.java:122)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:298)
at java.base/java.lang.Thread.run(Thread.java:831)

For details, please see GH action logs.