From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: is dynamic tick working? Date: Sun, 14 May 2006 03:49:18 -0700 Message-ID: <20060514104911.GB4715@atomide.com> References: <200605121905.13405.david-b@pacbell.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200605121905.13405.david-b@pacbell.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-omap-open-source-bounces+gplao-linux-omap-open-source=gmane.org@linux.omap.com Errors-To: linux-omap-open-source-bounces+gplao-linux-omap-open-source=gmane.org@linux.omap.com To: David Brownell Cc: linux-omap-open-source@linux.omap.com List-Id: linux-omap@vger.kernel.org * David Brownell [060512 19:05]: > On an OSK, using today's GIT tree, I turned on dynamic tick using > sysfs and thought the IRQ rate (32 KHz timer) was odd. So I did > > grep tim /proc/int*; sleep 60; grep tim /proc/int* > > and saw 104551 IRQs, which is 1742 per second. Too many!! When > I turned dyntick off (on/off via sysfs) the same measurement > gave a more reasonable 7701 IRQs, making 128 per second. > > In short, enabling dyntick got me 14x as many IRQs, instead of > shrinking the number of IRQs. Known bug? Is this with touchscreen enabled? I saw something similar last week where SPI was generating interrupts continuously. I think Imre has a patch for that already available. With dyntick the timer interrupt handler is being called also from other interrupt handlers to update time. So doing something like: $ cat /proc/interrupts; sleep 10; cat /proc/interrupts might give you a clue which device interrupt is stuck. In general dyntick should work, and you should see about 4-6HZ idle tick rate. Regards, Tony