From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Thu, 16 Nov 2006 02:07:19 +0000 Subject: RE: [PATCH] ia64 add idle loop entry/exit notifier Message-Id: <000f01c70923$f347c1e0$e034030a@amr.corp.intel.com> List-Id: References: <20061115222334.GE17238@frankl.hpl.hp.com> In-Reply-To: <20061115222334.GE17238@frankl.hpl.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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 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. - Ken