Messages in this thread | | | Date | Tue, 28 May 2002 21:55:35 +0530 | From | Dipankar Sarma <> | Subject | Re: 8-CPU (SMP) #s for lockfree rtcache |
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Hi Robert,
On Tue, May 28, 2002 at 08:49:58AM -0700, Robert Love wrote: > > > Well, the last time RCU was discussed, Linus said that he would > > like to see someplace where RCU clearly helps. > > I agree the numbers posted are nice, but I remain skeptical like Linus. > Sure, the locking overhead is nearly gone in the profiled function where > RCU is used. But the overhead has just been _moved_ to wherever the RCU > work is now done. Any benchmark needs to include the damage done there, > too.
Have you looked at the rt_rcu patch ? Where do you think there is overhead compared to what route cache alread does ? In my profiles, rcu routines and kernel mechanisms that it uses don't show high up. If you have any suggestions, then I can do an investigation.
> > I also balk at implicit locking... >
I agree that it is better to keep things simple and RCU isn't a replacement for locking. However the route cache hash table with refcount is a relatively simpler use of RCU and since it has benefits, we shouldn't shy away from using it if it is useful.
Thanks -- Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net Linux Technology Center, IBM Software Lab, Bangalore, India. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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