Corrigenda for Book

Corrigenda for Guerrilla Capacity Planning Book

Page Spotter Correction
p. 31  The Author Table in Example 3.5: Last entry s.b. 24 sigdigs. Must move decimal point 23 places to right.
p. 56  The Author Line 5 from bottom: σ−1 s.b. σ−1.
p.152  The Author Eqn.(8.1) should only have 4 random variables, not 6 X's. Two r.v.'s (MinU and MaxU in Fig. 8.5) are used to filter the data. The VBA code in Appendix E.2 is correct.
p.154  R. Schmitt Last line s.b.: "...larger values of Ueff are estimated..."

1  NOTES

1.1  J2EE and WebLogic Scalability

This is not a correction but additional information pertaining to Section 7.4.4, pp. 135 ff.

The following version numbers were supplied by Jamie Rybicki on Mon, Mar 24, 2008:
BEA WebLogic 9.1 with the BEA JRockit JDK 5.0 Update 6 (R26.4.0-63) 32 bit java virtual machine.
Regarding the WebLogic listen-threads hypothesis, originally due to Drew Sliwkowski (circa December 2005), 
Michael Ducy wrote on 3/24/08 12:06 PM: 
    This makes sense now that you tell me they are running the JRockit JVM.
    JRockit has the concept of "Thin Threads." Basically this is where M
    Java threads are ran inside N OS threads (or the MxN threading model,
    where M > N.) The JVM handles scheduling, synchronization, etc of these
    thin threads within the OS threads. I found an old JRockit developer
    article that indicated that N would most likely be set to the number of
    processors in the system.  This article was written when JRockit thin
    threads were still experimental. I am guessing BEA did some testing and
    found that 2N x CPUs performed better.
The interested reader may be able to find more in details in [J2EE Performance].

1.2  Scaled Speedup

This is not a correction but additional information pertaining to Section 4.3.5. p. 56.

The following diagram is useful for understanding the origin of eqn.(4.29).
The parallel portion of the work in Fig. 4.5 is first scaled up in proportion to the number of available processors: (1−σ) → (1−σ) p.
Then, it follows that the executions times are:

T1
= (1−σ) p T1 + σT1 (1st row of diagram)
(1)
Tp
=  (1−σ) p
p
 T1 + σT1 (2nd row of diagram) 
(2)
The ratio of these two times gives eqn.(4.29).
This kind of scale-up has recently been proposed as a way to optimize the throughput of multicores [Break Amdahl].

References

[J2EE Performance]
Peter Zadrozny, Philip Aston, and Ted Osborne,
J2EE Performance Testing with BEA WebLogic Server,
Expert Press, 2002.
[Break Amdahl]
Herb Sutter,
"Break Amdahl's Law!",
http://www.ddj.com/hpc-high-performance-computing/205900309


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On 7 May 2008, 10:58.