On 11/05/12 01:15, Russell King - ARM Linux wrote: > On Mon, Nov 05, 2012 at 09:23:38AM +0530, Taniya Das wrote: >> I was looking at the arch/arm/process.c:cpu_die, I was wondering why we >> do not exit from NOHZ for a hotplugged/offline cpu? > > Offlined CPUs are not supposed to just 'return' from cpu_die(), and > in actual fact they can't.
Although an offline CPU will not come back into the idle thread by returning from cpu_die(), I believe the question about exiting nohz mode before cpu_die() still stands. >From arch/arm/process.c:cpu_idle() it appears a CPU could enter pm_idle() for a while (in nohz mode), then execute the inner loop again and call cpu_die(). Is there the potential for cpu idle time accounting to get messed up here by not exiting nohz mode prior to the cpu dying, so that missed ticks from nohz are properly accounted for? thanks, Steve -- The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
