On Mon, 2007-05-14 at 13:58 +0200, Nick Piggin wrote: > On Fri, May 11, 2007 at 05:56:21PM +0200, Ingo Molnar wrote: > > > > * Peter Zijlstra <[EMAIL PROTECTED]> wrote: > > > > > I was toying with a scalable rw_mutex and found that it gives ~10% > > > reduction in system time on ebizzy runs (without the MADV_FREE patch). > > > > > > 2-way x86_64 pentium D box: > > > > > > 2.6.21 > > > > > > /usr/bin/time ./ebizzy -m -P > > > 59.49user 137.74system 1:49.22elapsed 180%CPU (0avgtext+0avgdata > > > 0maxresident)k > > > 0inputs+0outputs (0major+33555877minor)pagefaults 0swaps > > > > > > 2.6.21-rw_mutex > > > > > > /usr/bin/time ./ebizzy -m -P > > > 57.85user 124.30system 1:42.99elapsed 176%CPU (0avgtext+0avgdata > > > 0maxresident)k > > > 0inputs+0outputs (0major+33555877minor)pagefaults 0swaps > > > > nice! This 6% runtime reduction on a 2-way box will i suspect get > > exponentially better on systems with more CPUs/cores. > > Is this with the MADV_DONTNEED kernel and glibc work?
No, just the old stuff. > > > i also like the design, alot: instead of doing a full new lock type > > (with per-arch changes, extra lockdep support, etc. etc) you layered the > > new abstraction ontop of mutexes. This makes this hard locking > > abstraction look really, really simple, while the percpu_counter trick > > makes it scale _perfectly_ for the reader case. Congratulations! > > > > given how nice this looks already, have you considered completely > > replacing rwsems with this? I suspect you could test the correctness of > > Not to take anything away from this lock type (because it can have its > uses), but have you considered the size of this lock and its write side > performance? Yeah, I did, I was initially just toying about with the concept, to see if it was doable at all. I only posted because I got these fairly good numbers. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
