On Thu, Aug 02, 2007 at 11:33:39AM -0700, Martin Bligh wrote: > Nick Piggin wrote: > >On Wed, Aug 01, 2007 at 03:52:11PM -0700, Martin Bligh wrote: > >>>And so forth. Initial forks will balance. If the children refuse to > >>>die, forks will continue to balance. If the parent starts seeing short > >>>lived children, fork()s will eventually start to stay local. > >>Fork without exec is much more rare than without. Optimising for > >>the uncommon case is the Wrong Thing to Do (tm). What we decided > > > >It's only the wrong thing to do if it hurts the common case too > >much. Considering we _already_ balance on exec, then adding another > >balance on fork is not going to introduce some order of magnitude > >problem -- at worst it would be 2x but it really isn't too slow > >anyway (at least nobody complained when we added it). > > > >One place where we found it helps is clone for threads. > > > >If we didn't do such a bad job at keeping tasks together with their > >local memory, then we might indeed reduce some of the balance-on-crap > >and increase the aggressiveness of periodic balancing. > > > >Considering we _already_ balance on fork/clone, I don't know what > >your argument is against this patch is? Doing the balance earlier > >and allocating more stuff on the local node is surely not a bad > >idea. > > I don't know who turned that on ;-( I suspect nobody bothered > actually measuring it at the time though, or used some crap > benchmark like stream to do so. It should get reverted.
So you have numbers to show it hurts? I tested some things where it is not supposed to help, and it didn't make any difference. Nobody else noticed either. If the cost of doing the double balance is _really_ that painful, then we ccould skip balance-on-exec for domains with balance-on-fork set. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
