Messages in this thread | | | Date | Tue, 23 Jun 2009 05:59:20 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] v4 RCU: the bloatwatch edition |
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On Tue, Jun 23, 2009 at 11:48:46AM +0200, Ingo Molnar wrote: > > * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > > > On Mon, Jun 22, 2009 at 09:30:29AM -0700, Darren Hart wrote: > > > Paul E. McKenney wrote: > > >> On Mon, Jun 22, 2009 at 08:29:41AM -0700, Andrew Morton wrote: > > >>> On Mon, 22 Jun 2009 14:49:51 +0200 Ingo Molnar <mingo@elte.hu> wrote: > > >>> > > >>>> * David Howells <dhowells@redhat.com> wrote: > > >>>> > > >>>>> Hi Paul, > > >>>>> > > >>>>> Are you going to push your RCU patch for this merge window? > > >>>> Andrew needs to be convinced for that to happen. > > >>>> > > >>> whome? I rarely have firm opinions on anything. iirc the question > > >>> here was "is it worth adding another RCU implementation to save 900 > > >>> bytes"? > > >>> > > >>> I find it pretty hard to see how to come up with "yes" for that one but > > >>> it's hardly a huge issue. If you guys feel otherwise then go wild. > > >> Well, I do need to pull the "expedited" interface into the bloatwatch > > >> version, and my update of rcutorture made me realize that I can cut > > >> out a few more bytes, so I will submit an update. For what it is worth, > > >> here are the opinions expressed on LKML: > > >> + Ingo Molnar: good documentation, minimal RCU implementation. > > >> ? Andi Kleen: will there be !SMP systems in the future? > > >> + Lennert Buytenhek: there will be !SMP ARM for a long time. > > >> + Paul Mundt: good idea for more-constrained SH platforms. > > >> + David Howells: Acked-by. works on FRV board. > > >> ? Andrew Morton: do we really need another RCU implementation? > > >> Of course, I well remember programming systems with 4K of core memory > > >> back in the 1970s, and therefore feel a bit guilty about sticking deep > > >> embedded platforms with the increase in memory footprint represented > > >> by Hierarchical RCU compared to Classic RCU. And Bloatwatch RCU is much > > >> smaller and easier to understand/maintain than is Classic RCU. > > >> So, again, I will forward port, optimize, test, and resubmit. > > > > > > IIRC, in previous threads on this topic, the Bloatwatch edition was > > > expected to replace Classic RCU. If so, wouldn't that address Andrew's > > > concern of "adding" another implementation? > > > > Andrew expressed a preference for dropping Classic RCU without > > adding Bloatwatch RCU. ;-) > > Yes. In Linux there's no forced 'tie-in' of features and we'll > brutally untie them and use the most productive combination, if > justified technically ;-)
;-)
Thanx, Paul
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