Messages in this thread | | | Date | Wed, 18 Jun 2014 21:19:51 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [bisected] pre-3.16 regression on open() scalability |
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On Thu, Jun 19, 2014 at 04:50:19AM +0200, Mike Galbraith wrote: > On Wed, 2014-06-18 at 19:13 -0700, Paul E. McKenney wrote: > > On Wed, Jun 18, 2014 at 06:42:00PM -0700, Andi Kleen wrote: > > > > > > I still think it's totally the wrong direction to pollute so > > > many fast paths with this obscure debugging check workaround > > > unconditionally. > > > > OOM prevention should count for something, I would hope. > > > > > cond_resched() is in EVERY sleeping lock and in EVERY memory allocation! > > > And these are really critical paths for many workloads. > > > > > > If you really wanted to do this I think you would first need > > > to define a cond_resched_i_am_not_fast() or somesuch. > > > > > > Or put it all behind some debugging ifdef. > > > > My first thought was to put it behind CONFIG_NO_HZ_FULL, but everyone > > seems to be enabling that one. > > Not everybody, SUSE doesn't even have it enabled in factory.
OK, apologies for the over-generalization.
But you would think that I would have learned this lesson with CONFIG_RCU_FAST_NO_HZ, wouldn't you? :-/
Thanx, Paul
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