Messages in this thread | | | Date | Thu, 02 Aug 2007 11:33:39 -0700 | From | Martin Bligh <> | Subject | Re: [rfc] balance-on-fork NUMA placement |
| |
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.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |