Messages in this thread | | | Date | Mon, 16 Jul 2007 22:48:31 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH 1/8] Convert the RCU tasklet into a softirq |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Mon, 16 Jul 2007, Paul E. McKenney wrote: > > > > On Wed, Jun 27, 2007 at 03:36:34PM -0400, Steven Rostedt wrote: > > > I believe this was originally done by Dipankar Sarma. I pulled these > > > changes from the -rt kernel. > > > > > > For better preformance, RCU should use a softirq instead of a > > > tasklet. > > > > Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > > Tested with both kernbench and rcutorture on i386, x86_64, and ppc64. > > Btw, are there any numbers on this? Is this whole thing actually > noticeable?
i doubt it's noticeable, because the RCU tasklet was not a "true" global tasklet, it was an array of tasklets put into a PER_CPU array. (which kind of defeats the purpose of tasklets)
So there should be no/little scalability disadvantage from this type of use of tasklets, and the tasklet use was at most a wart and a small, constant micro-cost that is likely masked by other costs. (and rcu never used any of the fancier tasklet ops like tasklet_disable() either)
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