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Date: Mon, 16 Oct 2006 16:36:52 +0200 From: Andi Kleen <ak@...e.de> To: eranian@....hp.com Cc: linux-kernel@...r.kernel.org, akpm@...l.org Subject: Re: [PATCH] x86_64 add missing enter_idle() calls > With the original code, the number of callbacks you see for IDLE_START and > IDLE_STOP is not too obvious. > > On an idle system Opteron 250 with HZ=250, one would expect to see for a 10s duration: > - for CPU0 : IDLE_START = IDLE_STOP = about 5000 calls > - for other CPUs: IDLE_START = IDLE_STOP = about 2500 calls Yes. > With the original code, you get the following number of calls: > > CPU0.IDLE_START = 44 (enter_idle) > CPU0.IDLE_STOP = 5206 (exit_idle) > > CPU1.IDLE_START = 27 (enter_idle) > CPU1.IDLE_STOP = 2528 (exit_idle) > > Now, of course, you may get "batched" interrupts where you do not return to idle > before you process the next interrupt. But the difference seems quite high here. Shouldn't happen for timer interrupts. > > Do you have an explanation for this? Hmm, the last time I fixed this when you complained (post .18) i added a counter for entry/exit and verified that it was balanced. I haven't rechecked since then. I don't know why your numbers are off. You're using the latest git tree, right? -Andi - 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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