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On Mon, May 10, 2004 at 09:54:04AM -0500, Matt Mackall wrote: > On Mon, May 10, 2004 at 02:46:58AM -0700, Andrew Morton wrote: > > Arjan van de Ven <arjanv@redhat.com> wrote: > > > > > > On Mon, 2004-05-10 at 10:27, Helge Hafting wrote: > > > > Matt Mackall wrote: > > > > > > > > >One also wonders about whether all the RCU stuff is needed on UP. I'm > > > > >not sure if I grok all the finepoints here, but it looks like the > > > > >answer is no and that we can make struct_rcu head empty and have > > > > >call_rcu fall directly through to the callback. This would save > > > > >something like 16-32 bytes (32/64bit), not to mention a bunch of > > > > >dinking around with lists and whatnot. > > > > > > > > > >So what am I missing? > > > > > > > > > > > > > > Preempt can happen anytime, I believe. > > > > > > ok so for UP-non-preempt we can still get those 16 bytes back from the > > > dentry.... > > > > I suppose so. And on small SMP, really. We chose not to play those games > > early on so the code got the best testing coverage. > > Ok, I can spin something up. I'll start with a generic no-RCU-on-UP > and then we can think about the small SMP case a bit later. Hello, Matt, You may wish to start with the dcache portion of Dipankar's earlier patch: http://sourceforge.net/mailarchive/forum.php?thread_id=3644163&forum_id=730 It does not remove the extra rcu_head from the dentry, but does the rest of the work. Thanx, Paul - 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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