Machine Architecture slides back online

http://herbsutter.wordpress.com/2010/02/22/machine-architecture-slides-back-online/

by wglb • 16 years ago

7 2 16 years ago

herbsutter.wordpress.com

nir• 16 years ago

I can't believe this only gets 3 points in HN. Perhaps try adding some reference to Jason Calcanis in the title.

nchong• 16 years ago

Yup, these are great slides, especially pg 11-14 about memory models.

Weakly consistent memory models contain all sorts of horrors for programmers that think sequentially consistently. Can the following program throw an assertion error?

  //Initially, x = y = 0
  Processor 1: x = 1;
  Processor 2: while (x == 0) {/*do nothing*/}; y = 1;
  Processor 3: while (y == 0) {/*do nothing*/}; assert (x == 1);

(On an ARM processor this assertion can legally fire (x can equal 0 for Processor 3); and you can s/Processor/Thread/ and still have this result hold)

Volume 3A of the Intel Architecture Manual is worth a read if you like these type of puzzles (http://www.intel.com/products/processor/manuals/).

For those that want a formal approach then good things are happening in Cambridge: http://www.cl.cam.ac.uk/~pes20/weakmemory/

Machine Architecture slides back online

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