Hi Dave, Chapel's performance has significantly improved over the last few releases, so it's surprising that you would see a 2X slowdown after upgrading. Without seeing the code, my initial guess is that you might be getting bad first-touch for some arrays now. Prior to 1.11 we serially initialized arrays, but we switched to parallel initialization by default in 1.12. If you're using a machine with multiple numa domains (it sounds like you are since you have multiple cpus) and your code is serial, this could cause a slowdown.
You can check if parallel array initialization is causing the slowdown by compiling with `-sparallelInitElts=false` and seeing if you get your old performance back. That's a big hammer, but it will at least tell us if that's the cause of the performance loss. Feel free to send your code along, and note that there's no problem with installing multiple versions of Chapel. Elliot >We've upgraded from Chapel 1.11 to 1.13 recently, and we're seeing a >drop-off in performance (by about a factor of two) of our Chapel code for >Nussinov's Algorithm for RNA sequence alignment. Has anyone else noticed a >difference? Does anyone have easy access to both 1.11 and 1.13 and time to >verify this result if I send the specific code? We could perhaps try to >install two versions at once, but if this is a known problem, I don't want >to bother, and if it is new, I thought this might be easier for the >developers to confirm, and interesting if it is indeed a change. > >Note that we also did a hardware upgrade recently, and it is possible that >the old numbers come from the old hardware, but I wouldn't expect an >hardware upgrade to make things slower ... in case anyone cares, we went >from first-generation i7's (i7-860, I think?) to new i5-6500's, and this is >a single-threaded code. > >Thanks for any insight anyone can provide, > Dave Wonnacott ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Chapel-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/chapel-users
