On Wed, 11 Mar 2015 11:34:25 +0100 Heinz Diehl <htd+ml@xxxxxxxxxx> wrote: > I just tried a simple "make" on an 8-core machine. There was exactly > one compile process, and it's 100% load was distributed over 3 cores. > So nothing wrong with that one. If you run 100% on one core or 100% > distributed over multiple cores is, in terms of efficacy, the same. This is my experience as well. > It's the limiting to one process which causes what you observe. 1 > process can not get more resources that 100%. The CPU scheduler > handles how they are distributed. I think this is the key. What is the point of -j6 or -j8 if the make can't spawn additional processes with their own limits, and thus take advantage of more resources that are available? What is it that limits a process and its children from using more resources than a single core, even though they are available? > Ondemand and performance affect the cpufreq, not the load balancing > or the involvement of different cores. Thanks, learn something every day. > No. It keeps every core running at full speed all the way, which has > nothing to do with how the load is balanced between different cores. Can you point me to which area of the kernel has the code that does the actual load balancing? Maybe it would be easy to do a custom patch that bypasses this limiting behavior. I understand that parallel computing requires parallel programming in the code, but I'm thinking more of letting make have more than a single core available. As you point out above, it is already using multiple cores. I just want it to be able to use all of those multiple cores if they are available. > > > I'll keep plugging away, reading and experimenting, until I get it > > or give up. > > Use "make -j" when compiling and be happy :-) Truly, it will probably come to this. I can then start the job and let it run in the background with no impact to other things I am doing. What I was hoping was that when I wanted to run things overnight, I could kick off a couple of compute intensive jobs, and they would share all the resources of the computer until they were done. With no impact to my use of the computer because I wouldn't be interacting with it. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
