On Mar 24, 2017, at 6:10 PM, Reuti <re...@staff.uni-marburg.de> wrote: > >> - Disabling HT in the BIOS means that the one hardware thread left in each >> core will get all the cores resources (buffers, queues, processor units, >> etc.). >> - Enabling HT in the BIOS means that each of the 2 hardware threads will >> statically be allocated roughly half the core's resources (buffers, queues, >> processor units, etc.). > > Do you have a reference for the two topics above (sure, I will try next week > on my own)? My knowledge was, that there is no dedicated HT core, and using > all cores will not give the result that the real cores get N x 100%, plus the > HT ones N x 50% (or alike). But the scheduler inside the CPU will balance the > resources between the double face of a single core and both are equal.
I'm not quite sure I can parse your above statements. I should be clear: I was referring to Intel server core processors. It may be the same across all the Intel core processors, but I do not have direct knowledge of that. I'm afraid I don't have specific citations; you'll just have to look in the Intel docs. In addition to what Tim said, I should note that a core is just a collection of resources. When you enable HT, a) there's 2 hardware threads active, and b) most of the resources in the core are effectively split in half and assigned to each hardware thread. When you disable HT, a) there's only 1 hardware thread, and b) the resources of the core are allocated to that one hardware thread. I'm speaking in generalities; go read the Intel docs for more specifics. > My personal experience is, that it depends not only application, but also on > the way how you oversubscribe. +1 -- Jeff Squyres jsquy...@cisco.com _______________________________________________ users mailing list users@lists.open-mpi.org https://rfd.newmexicoconsortium.org/mailman/listinfo/users
