Consider the following situation.  A thread acquires a mutex, then enters a critical section.  However when executing in the critical section, the thread access a memory location.  If that memory location is not in cache, the thread will wait for a few hundred cycles.  If accessing the memory location causes a page fault (the memory was swapped out to disk), the thread may need to wait a few million cycles.  However while this thread is waiting, it is still holding the mutex.  This means that other threads will not be able to enter the critical section, and may

It has been a while since my last post.  I'm sorry about that, but I have been busy trying to the fix bugs reported as part of the Maple Beta program.  I'm also running low of good parallel programming topics.  So, as always, if you have topics you'd like to hear about (or hear more about) feel free to ask.

Today I am going to post a brief note about a blog that I find quite interesting.

Cliff Click Jr's Blog: http://blogs.azulsystems.com/cliff/

I realized the other day that I had not mentioned the Threads:-Add, Threads:-Map, Threads:-Mul and Threads:-Seq functions.  These are parallel implementations of the standard Maple functions, add, map, mul and seq.  They expect the sam

This post is a quick book review of

The Art of Multiprocessor Programming
by Maurice Herlihy and Nir Shavit

Yesterday I attended a lecture by Fran Allen, as part of the "David R. Cheriton School of Computer Science, University of Waterloo, Distinguished Lecture Series".  Allen worked a IBM Research from 1957 to 2002, she was awarded the ACM's Turing Award in 2006.  Here is her biography from Wikipedia (let's hope it is accurate). 

Aside from some technical issues (why can't a room full of computer science professors and students successfully attach a laptop to a projector?) the talk was quite interesting.  There were two main sections, the first discussed Allen's career at IBM and the second was about the future of computer science.  Allen's work at IBM focused mostly on compilers and high performance computing.  She made a few interesting comments about the importance of high performance computing.  For example, one of the systems she worked on was designed and used to model the detonations of nuclear weapons.  The development of this system ended the need for the United Stated to perform actual test detonations.