(j3.2006) Question from a colleague

Jim Xia jimxia
Tue Apr 7 15:55:20 EDT 2009

A few releases back, our compiler supported two versions of run-times: 
thread-safe and non thread safe.  And we did find some programs benefited 
from non thread-safe RT.  However it was also found that most "performance 
hit" can be avoided by re-arrange the code to minimize the locking 


Jim Xia

XL Fortran Compiler Test
IBM Toronto Lab at 8200 Warden Ave, Markham, On, L6G 1C7
Phone (905) 413-3444  Tie-line 313-3444
email: jimxia at ca.ibm.com
D2/YF7/8200 /MKM

Van Snyder <Van.Snyder at jpl.nasa.gov>
j3 <j3 at j3-fortran.org>
04/07/2009 02:38 PM
(j3.2006) Question from a colleague

A colleague asked me whether there is a performance benefit if the
compiler is informed that it is not necessary for a procedure to be
thread safe.  This actually originated in a discussion of iterators in
python, CLU and alphard, where the activation record has to be preserved
between suspension and resumption, as for a coroutine.  My colleague did
ask, however, whether our code would run faster if we could tell the
compiler it didn't need to be thread safe.  We use 5 million cpu hours
per year, so a little improvement makes a big difference.

Van Snyder                    |  What fraction of Americans believe 
Van.Snyder at jpl.nasa.gov       |  Wrestling is real and NASA is fake?
Any alleged opinions are my own and have not been approved or
disapproved by JPL, CalTech, NASA, the President, or anybody else.

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