I wish I could play with one of those Connection machines and find out about the bottlenecks at j=0.25*cpus that I can see on some machines :-(
Regards, Tim On 15 April 2011 19:32, Howard Chu <h...@highlandsun.com> wrote: > Eli Zaretskii wrote: >>> >>> Date: Fri, 15 Apr 2011 10:37:13 -0400 >>> From: David Boyce<david.s.bo...@gmail.com> >>> it's more a question of how many parallel jobs a given make process is >>> managing since limits on file handles/descriptors are per process. >> >> What about people who use "make -j" without limits? > > They're idiots. I've never seen a machine that can handle more than 1.5x > number of cores without getting bottlenecked by I/O or system scheduler. > (And I've run this stuff on 1024 node Connection Machines, among other > things...) Go above a certain threshold and you're only slowing yourself > down. > >> It's not like having a 256-core machine is a fantasy that will not >> happen in a few years. On my day job, we are already using 12 cores >> and don't consider that "living on the edge". > > We've already seen bug reports from people running on machines with 4096 > cores, trying to run with -j8192 or somesuch. (Default pipe buffer is 4K > which sets -j4096 as the practical limit without mucking with kernel > params.) > > -- > -- Howard Chu > CTO, Symas Corp. http://www.symas.com > Director, Highland Sun http://highlandsun.com/hyc/ > Chief Architect, OpenLDAP http://www.openldap.org/project/ > > _______________________________________________ > Bug-make mailing list > Bug-make@gnu.org > http://lists.gnu.org/mailman/listinfo/bug-make > -- You could help some brave and decent people to have access to uncensored news by making a donation at: http://www.thezimbabwean.co.uk/ _______________________________________________ Bug-make mailing list Bug-make@gnu.org http://lists.gnu.org/mailman/listinfo/bug-make