Hello Vijay, Thank you for your answer.
However, I have two more questions. 1) > For the duration of the X10 program, "idle" workers are constantly searching for work. Does it mean that thread is polling to find a job? 2) I found that the sequential Fibonacci program runs much slower with 24 threads than with 1 thread. Following shows the results. -INIT_THREADS=24, execution time of Fib(40) =108.35 sec -INIT_THREADS=1, execution time of Fib(40) =8.16 sec It means that the sequential program in X10 performs bad on multi-core platform. Is it related to the fork/join scheduler implementation? Regards, -Tetsu On 07/12/2010 06:51 PM, Vijay Saraswat wrote: > Added the following to the X10 Languages FAQ, > http://docs.codehaus.org/display/XTENLANG/X10+Language+Features+FAQ. > > > Why are all cores active when I run a sequential X10 program > on the Java backend? > > X10 implements async using a user-space scheduler (a ForkJoin > scheduler in v2.0.4). This scheduler starts with a given set of > workers (see How do I control the size of the thread pool in a place? > <http://docs.codehaus.org/display/XTENLANG/X10+Language+Features+FAQ#X10LanguageFeaturesFAQ-THREADSPOOLSIZE>). > > For the duration of the X10 program, "idle" workers are constantly > searching for work. In the Java backend, the number default to > availableProcessors(), hence all cores are busy. > > > How do I control the size of the thread pool in a place? > > For the C++ backend, set the environment variable X10_NTHREADS to > control the number of initial workers in a place. For the Java > backend, provide the -INIT_THREADS command-line option. (This defaults > to availableProcessors().) > > Note that the ForkJoin scheduler in X10 2.0.4 may create more workers > if the current worker suspends (e.g. to execute a when). > > See X10 Runtime presentation at X10 Day > <http://docs.codehaus.org/download/attachments/140575067/X10_Runtime.pdf?version=2&modificationDate=1271426365763> > > for more details. > > > Tetsu Soh wrote: >> Hello everyone, >> >> I run a serial Fibonacci program(without multi-activity programming) on >> a 24-core Linux box with Java back-end X10 2.0.4 and found that all >> cores were active. How it comes? Is it because the thread pool that >> employed in Java-back end is always working? >> And is there any way to control how many threads should be active in the >> thread pool in the case that I don't want all my cores are used to run >> the X10 program? >> >> Thank you in advance. >> -Tetsu >> >> ------------------------------------------------------------------------------ >> This SF.net email is sponsored by Sprint >> What will you do first with EVO, the first 4G phone? >> Visit sprint.com/first --http://p.sf.net/sfu/sprint-com-first >> _______________________________________________ >> X10-users mailing list >> X10-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/x10-users >> ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first _______________________________________________ X10-users mailing list X10-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/x10-users
