Ken, On Wed, Nov 15, 2006 at 06:07:19PM -0800, Chen, Kenneth W wrote: > Stephane Eranian wrote on Wednesday, November 15, 2006 2:24 PM > > Here is a patch which adds an idle notifier to IA-64. It clones > > the one in X86-64. You can register a callback via the notifier > > and you get called when: > > - entering the lowest level of the idle loop > > - exiting the lowest level of the idle loop, either normally > > or to process an interrupt > > > > Basically, you can monitor useful vs. useless work accomplished > > by the idle thread on each processor. > > Is idle notifier a light weight callback thingy? I happen to work Well, it uses the notifier interface. I have not changed this part. > on an application environment that cycles CPUs into gazillion nano > second sleep due to tons of sleep / wake up activity from thousands > of processes. I'm just checking and hope this notifier chain isn't > going to add significant overhead when cycling through busy/idle. > I would suggest you measure the overhead when no callback is registered. The patch is such that there will systematically be a callback registered for SGI machines. But if you are cycling busy/idle, I would think that you biggest cost if coming out of PAL_HALT. -- -Stephane - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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