Messages in this thread | | | Subject | Re: load balancing regression since commit 367456c7 | From | Tim Chen <> | Date | Tue, 17 Apr 2012 09:44:14 -0700 |
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On Tue, 2012-04-17 at 14:09 +0200, Peter Zijlstra wrote: > On Tue, 2012-04-10 at 18:06 -0700, Tim Chen wrote: > > |--56.52%-- load_balance > > | idle_balance > > | __schedule > > | schedule > > Ahh, I know why I didn't see it, I have a CONFIG_PREEMPT kernel and > idle_balancing stops once its gotten a single task over instead of > achieving proper balance. > > And since hackbench generates insanely long runqueues and the patch that > caused your regression 'fixed' the lock-breaking it will now iterate the > entire runqueue if needed to achieve balance, which hurts. > > I think the patch I send ought to work, let me try disabling > CONFIG_PREEMPT. > --
yes, CONFIG_PREEMPT is turned off on my side. With the patch that you sent, the slowed down went from a factor of 4 down to a factor 2.
So the run time is now twice as long vs four time as long vs v3.3 kernel.
Tim
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