Page 1 of 1

Win64 multi core not always used ?

Posted: Sat Aug 31, 2013 12:04 pm
by CCD1024
Dear Ivo
I use Startools 64 on a brand new computer under win8 64 and core i7 3970X (6 cores / 12 threads)
As I compute 4096x4096 images with star repair process, I saw the WARP function only use 1 processor core when MODIFYING STAR (long) and the 12 threads when HEALING process.
So, this very slow down the process !

Is it normal ?


Re: Win64 multi core not always used ?

Posted: Sun Sep 01, 2013 6:03 am
by admin
Hi Philippe,

This is indeed expected behaviour. The effectiveness of making an algorithm multi-threaded, greatly depends on the nature of the algorithm. Algorithms that perform a lot of calculations but access little data are most effectively distributed across multiple threads, whereas algorithms that require a lot of memory access (the warp algorithm is such an algorithm) are much less effective when multi-threaded (they can even be slower!). The reason for the latter is that such memory-heavy threads are all constantly waiting for the memory bus in that case.
That said, I'm constantly looking for optimizations and it's probably a good idea to do some tests to see if we can optimize the warp algorithm some more. Multi-threading may yet play a role in this! :thumbsup:

Re: Win64 multi core not always used ?

Posted: Mon Sep 02, 2013 12:16 pm
by CCD1024
Hi Ivo
Thanks... I understand :doh: