From mboxrd@z Thu Jan 1 00:00:00 1970 From: vikram186@gmail.com (Vikram Narayanan) Date: Sun, 24 Apr 2011 19:50:55 +0530 Subject: Architecture specific implementations for tickless kernel and deferrable timers In-Reply-To: <4DB0F249.6000307@codeaurora.org> References: <4DB0F249.6000307@codeaurora.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Apr 22, 2011 at 8:43 AM, Jeff Ohlstein wrote: > Vikram Narayanan wrote: >> And also, are clocksoure and clockevents dependent on each other? I >> see in some platforms, that they have used 2 different timers for the >> above. Can a same clock be used for both clocksource and clockevents? >> Please throw some light on this. If it can be used so, what ties up >> the clocksource and clockevent? > > You can look at msm for an example of a single timer being used both as > a clocksource and a clockevent. We end up shutting off the clocksource > whenever we shut down the clockevent. This does cause some issues. > Switching clocksources at runtime does not work. It will also cause > problems if you implement your own sched_clock function, as it will have > little choice but to return a stale cached value whenever the clockevent > is disabled, such as in the suspend path. Thanks for the example. I will refer to that. And I have another question, If dynamic ticks are implemented, say if I am using the same clocksource and clockevent, the wall time will only be updated at that dyn_tick interval. Will that create any issue? or should I use a constant source for the clocksource? or how to handle this in an effective way. * Clocksource and clockevents with the same timer. * Also I want to make use of the tickless kernel functionality. Vikram > > Jeff > > -- > Sent by an employee of the Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. >