Benoit, > -----Original Message----- > From: linux-omap-ow...@vger.kernel.org [mailto:linux-omap- > ow...@vger.kernel.org] On Behalf Of Cousson, Benoit > Sent: Friday, August 27, 2010 3:56 PM > To: vishwanath.sripa...@linaro.org; Sripathy, Vishwanath > Cc: linux-omap@vger.kernel.org; linaro-...@lists.linaro.org; Jean Pihet; > Chalhoub, Nicole; Bour, Vincent > Subject: Re: [PATCH] OMAP CPUIDLE: CPU Idle latency measurement > > Hi Vishwa, > > On 8/28/2010 12:08 AM, vishwanath.sripa...@linaro.org wrote: > > From: Vishwanath BS<vishwanath.sripa...@linaro.org> > > > > This patch has instrumentation code for measuring latencies for > > various CPUIdle C states for OMAP. Idea here is to capture the > > timestamp at various phases of CPU Idle and then compute the sw > > latency for various c states. For OMAP, 32k clock is chosen as > > reference clock this as is an always on clock. wkup domain memory > > (scratchpad memory) is used for storing timestamps. One can see the > > worstcase latencies in below sysfs entries (after enabling > CONFIG_CPU_IDLE_PROF > > in .config). This information can be used to correctly configure cpu > idle > > latencies for various C states after adding HW latencies for each of > > these sw latencies. > > /sys/devices/system/cpu/cpu0/cpuidle/state<n>/actual_latency > > /sys/devices/system/cpu/cpu0/cpuidle/state<n>/sleep_latency > > /sys/devices/system/cpu/cpu0/cpuidle/state<n>/wkup_latency > > FYI, Jean is currently working on using standard Linux probes in order > to instrument CPUIdle / CPUfreq. I'm not sure it is doable, but it might > better to use standard method to do that instead of purely OMAP3 > specific stuff. This code will not scale easily on OMAP4. > Just discussed how to scale this for all OMAPs. Firstly we need to get this code to common place instead of tying it to OMAP3/OMAP4 specific low level code. Since on OMAP3, we can push C-functions on SRAM and for OMAP4 we don't have any limitation, all this code can be converted to C.
Vishwa is planning to attempt that in next version. Regards, santosh -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
