Messages in this thread | | | Date | Mon, 06 Jul 2015 16:09:31 +0100 | From | Sudeep Holla <> | Subject | Re: [patch 1/2] tick/broadcast: Prevent deep idle states if no broadcast device available |
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Hi Thomas,
On 05/07/15 21:53, Thomas Gleixner wrote: > If no broadcast device is installed and the cpu local timers stop in > deeper idle states, then there is currently nothing telling the idle > code that it should not go into deep idle states, so the timers stop > and nothing wakes up the cpus. > > Make the broadcast_enter/exit() functions independent of the > configuration options and always check on enter: > > - whether the cpu local device is affected by idle states > - whether a broadcast device is available > > This covers all possible config combinations including > CONFIG_BROADCAST=n. > > Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Sorry for the delay, took a while testing few configuration:
+--------------+--------+--------------+--------------------+ | Configs | PERIOD | HRTimers+NOHz|Cmdline(HR+NoHZ=off)| +--------------+--------+--------------+--------------------+ | UP w/o H/W BC| OK | OK | OK | +--------------+--------+--------------+--------------------+ | UP w/ H/W BC | OK | OK | OK | +--------------+--------+--------------+--------------------+ |SMP w/o H/W BC| OK* | OK | Not OK(**) | +--------------+--------+--------------+--------------------+ |SMP w/ H/W BC | OK | OK | OK | +--------------+--------+--------------+--------------------+
H/W BC - Hardware Broadcast Timer source
(*) None of the CPUs enters deeper idle states losing local timers
(**)SMP build without Hardware Broadcast Timer source(i.e. one cpu is the broadcast source) with HRTimers+NOHz configs but disabled in cmdline fails to boot. On connecting debugger, I found all the cpus are in shallow idle state(i.e. WFI in ARM) but with interrupts disabled.
I am not really keen on the failing configuration. We have never tested that before, though I found it working with CPUIdle disabled.
So please feel free to add: Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Regards, Sudeep
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