JDK-8195117 : Performance regressions from JDK-8186027
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 10
  • Priority: P3
  • Status: Closed
  • Resolution: Duplicate
  • OS: linux,os_x,solaris
  • CPU: sparc,x86_64
  • Submitted: 2018-01-16
  • Updated: 2018-01-19
  • Resolved: 2018-01-19
Related Reports
Duplicate :  
JDK-8195118 - LoopStripMining causes performance regression
Relates :  
JDK-8186027 - C2: loop strip mining
Description
Looks like JDK-8186027 is causing a few performance regressions:

��� ~ 1.5% in SPECjbb2005-G1	on Solaris-SPARC

��� 2-5% in SHA1PRNG crypto benchmarks on Linux-x64, Mac-x64, and Solaris-SPARC:
   ��� micro.benchmarks.crypto.small.SecureRandomBench.nextBytes-algorithm:SHA1PRNG-dataSize:64-provider:-shared:false
   ��� micro.benchmarks.crypto.small.SecureRandomBench.nextBytes-algorithm:SHA1PRNG-dataSize:64-provider:-shared:true

Regressions hold at least through b39.

Reproduces in triage (reproduction run on same machine).
Reproduces in re-triage (reproduction run on different machine).
VMswap results indicate the cause is in the JVM.

Measurements of b36 using -XX:-UseCountedLoopSafepoints show the regressions go away. So the cause appears to be JDK-8186027
Comments
I'm closing this as duplicate of JDK-8195118 (will move the relevant information).
19-01-2018