Thank you all for the valuable information and suggestions, they help a lot!
Janet ________________________________________ From: Rayson Ho [[email protected]] Sent: Thursday, October 27, 2011 1:32 PM To: Reuti; He, Janet (NIH/NIAID) [C]; [email protected] Subject: Re: [gridengine users] Questions about SGE On Thu, Oct 27, 2011 at 1:01 PM, Reuti <[email protected]> wrote: >> 4. If a node is hyper-threading enabled, should we count the real core >> number in SGE or using the hyper-threading core number in SGE, i.e for >> 8-core node, with hyper-threading, the core becomes 16. Should SGE uses 8 >> or 16 in the configuration? > > This depends on the application. I found by some test runs that > Hyperthreading will give around 1.5 times the performance for our > applications but won't double it. To be on the safe side also for other > applications, I turn Hyperthreading always off and use the real number of > cores. And also depends on the processor architecture... For newer Core i7 based processors, as the processor is smarter with hardware thread scheduling (inside the chip), you get a much better chance of getting better job throughput (but of course each job would run slightly slower, but not by much). For Pentium 4 processors, just turn Hyperthreading completely off!! Hyperthreading on the Pentium 4 can easily cause slowdown because the *whole chip* is like a hack, see the undocumented (but existence confirmed by an ex-Intel architect, Bob Colwell) replay feature: http://en.wikipedia.org/wiki/Replay_system Lastly, for memory bound HPC / fortran code, Hyperthreading almost always won't help as memory bandwidth is the bottleneck. Rayson > > -- Reuti > _______________________________________________ > users mailing list > [email protected] > https://gridengine.org/mailman/listinfo/users > _______________________________________________ users mailing list [email protected] https://gridengine.org/mailman/listinfo/users
