[HADOOP-7401] Unit test TestPureJavaCRC32 warmup code warms up the not-so-important loop in PureJavaCRC32.update()

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 0.21.0
• Fix Version/s: 0.21.0
• Component/s: test

Environment

Solaris-Sparcv9; Solaris-AMD64

• Release Note: fixed warmup in the perf test.
• Assignee: monica beckwith
• Reporter: monica beckwith
• Created: 17/Jun/11 15:22
• Updated: 19/Jul/12 17:56

Description

When the warmup code sequence in TestPureJavaCRC32.java is executed, it sends size=len=2 and due to the value of 'trials' in for loop in doBench(), the crc.update() gets run > the compile threshold, thus providing the information that 'while 0<len<7' is a hot loop and 'while len>7' is a cold loop. This brings the MB/s number for len > 7 in PureJavaCRC32.update() way down (e.g. ~28.5% for size=len=65536).

The workaround would be to use size=len=>7 (so just having size=len=2101 ahead of size=len=2 will do the trick) in the warmup section.

Issue Links

• is related to: HADOOP-6148 Implement a pure Java CRC32 calculator