Re: PM / Suspend: Print wall time at suspend entry and exit

[Mark Salyzyn]

On 06/05/2017 02:47 PM, Mark Salyzyn wrote:
> On 06/05/2017 02:18 PM, Pavel Machek wrote:
> > Hi!
> >
> > > On Mon, Jun 5, 2017 at 9:31 PM, Mark Salyzyn <salyzyn@xxxxxxxxxxx> 
> > > wrote:
> > > > Permits power state and battery life diagnosis.
> > > Which is possible even without this patch and we have tools for that
> > > (analyze_suspend.py, anyone?).
> > >
> > > Honestly, I don't see why this change is necessary or even useful.
> > I ran dmesg after resume and now I...
> >
> > [1019729.486249] ACPI : EC: EC stopped
> > [1019729.486255] PM: Saving platform NVS memory
> > [1019729.486276] Disabling non-boot CPUs ...
> > [1019729.490423] smpboot: CPU 1 is now offline
> > [1019729.531015] smpboot: CPU 2 is now offline
> > [1019729.577742] Broke affinity for irq 16
> > [1019729.577747] Broke affinity for irq 17
> > [1019729.577751] Broke affinity for irq 19
> > [1019729.577756] Broke affinity for irq 23
> > [1019729.578771] smpboot: CPU 3 is now offline
> > [1019729.604987] ACPI: Low-level resume complete
> > [1019729.605052] ACPI : EC: EC started
> > [1019729.605054] PM: Restoring platform NVS memory
> > [1019729.605352] Suspended for 3196.166 seconds
> > [1019729.605376] Enabling non-boot CPUs ...
> > [1019729.631246] x86: Booting SMP configuration:
> > [1019729.631249] smpboot: Booting Node 0 Processor 1 APIC 0x1
> > [1019729.631496] Initializing CPU#1
> > [1019729.631514] Disabled fast string operations
> > [1019729.636643]  cache: parent cpu1 should not be sleeping
> > [1019729.637286] CPU1 is up
> >
> > Aha. I missed the "suspended for 3196" message before. So I believe
> > you are right; there's already enough information in the kernel logs.
> >
> >                                     Pavel
>
> We do not get the Suspended for messages on failure to suspend 
> (interrupt wakeup), but that is a weak argument ;-/ since it is 
> discoverable from context and we can count the aborted suspends 
> switching the tools. The Suspended for messages are in ms which is not 
> accurate enough for Android user space logs (in ns) long term 
> continuous tracking of monotonic vs realtime and makes no accounting 
> for ntp adjustments. Currently, post mortem data only on Android, we 
> have no other way to align monotonic kernel logs with user space logs 
> without this.
>
> Sincerely -- Mark Salyzyn
Also, not all devices have a persistent time that can be collected at 
Suspend at that level, so they have to turn off CONFIG_SUSPEND_TIME 
because 'Suspended for' is meaningless on those platforms, but alas 
these prints turn into a backup mechanism for those platforms as they 
are printed befopre and after the hardware is up and running.

-- Mark