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Date: Sun, 29 Mar 2009 11:25:10 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Paul Mackerras <paulus@...ba.org> Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org, Mike Galbraith <efault@....de>, Arjan van de Ven <arjan@...radead.org>, Wu Fengguang <fengguang.wu@...el.com>, Eric Dumazet <dada1@...mosbay.com> Subject: Re: [PATCH 1/9] perf_counter: unify and fix delayed counter wakeup On Sun, 2009-03-29 at 11:16 +0200, Peter Zijlstra wrote: > On Sun, 2009-03-29 at 11:14 +1100, Paul Mackerras wrote: > > Peter Zijlstra writes: > > > > > While going over the wakeup code I noticed delayed wakeups only work > > > for hardware counters but basically all software counters rely on > > > them. > > > > Hmmm, I don't like the extra latency this introduces, particularly > > since on powerpc we already have a good way to avoid the latency. > > Right, so I can re-instate the powerpc bits and have it call > perf_counter_do_pending() whenever it finds the per-cpu pending bit set. > > I'd have to look into the fancy new per-cpu stuff for the x86 bits, but > I'm reasonably sure something like that should be doable. In a perfect world, I'd introduce a self-ipi on UP and use that. Also, in that same perfect world, all arches would support cmpxchg()/xchg() so we could put the whole thing in generic code. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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