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Questions for Jolla Tablet owners (about battery and CPU usage)

asked 2016-02-24 13:22:41 +0300

updated 2016-02-24 16:06:34 +0300

As I've stated in another thread, I managed to get an unofficial Tablet (sorry about that). It looks genuine, but... What I'd like to do is to gather some user experience mainly from people who have the real one. The main reason is to find out whether my device behaves like genuine so that I'll know whether it's relevant for me to answer Tablet related questions in this forum and develop workarounds ;). So far it looks like the answer is yes (at least regarding the brightness issues). But we'll see.

  1. What number do you have in Settings/About Product/Hardware Adaptation?
  2. How often do you have to charge?
  3. How long is your battery life in idle?
  4. If you are using System Monitor (https://openrepos.net/content/abranson/system-monitor-tablet-edition), what percent of CPU usage you'll get when the device is on idle?

(And my answers:

  2. Every other day
  3. 48 h
  4. 76 %, but if the charger is attached the number drops to approximately 1 %)
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Idle battery life is only 48 hours? Really? My now over four year old Android tablet can lay idle for several weeks.

nthn ( 2016-02-24 16:12:01 +0300 )edit

@nthn Well, that 48h is probably with wlan connected and I can assure that it won't do any better with Android.

tigeli ( 2016-02-24 18:34:31 +0300 )edit

I am more conserned over the 76% CPU usage while idle. There's something happening there.

jollailija ( 2016-02-24 18:45:10 +0300 )edit

@tigeli, disconnecting wlan doesn't affect the battery life nor CPU usage while idle.

@jollailija, yes that's my assumption too. If someone with an official tablet will answer, we'll hopefully find out whether this is an error in Tablet version of Sailfish OS (or a misunderstood feature of the System Monitor app) or something that shouldn't be there in the first place (which would make this just my personal problem to be handled outside this forum).

Moshroom ( 2016-02-24 18:55:16 +0300 )edit

@Moshroom Well disabling wlan does affect on my tablets battery life. Can't tell about System Monitor app though..

edit: Just checked that my tablet's cpu is 97% idle when running top in terminal (without charger being connected).

tigeli ( 2016-02-24 19:02:08 +0300 )edit

8 Answers

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answered 2016-03-04 06:24:31 +0300

codeandcreate gravatar image

updated 2016-03-07 12:33:40 +0300

I have the official one and it doesn't really matter if i use it or not if it is on. besides carddav/caldav sync (daily) and 3 mail accounts (30min) i dont't have any background tasks aktive. since i got it on monday i don't have any long time view on battery life but i think there is no real powersaving mode (Jolla, please comment on this!), when you turn the display off.

  2. less than 24 h (read rss feeds, surfing,... ) ~ normal use
  3. 24 - 48 h ?
  4. around 1.5%

my last tablet was a Samung Galaxy Tab 7.7. with the same normal usage i got about a half till a week battery life and with no usage more than 2 weeks.

Update: The Android Runtime really eats a lot of power. if i close it, the battery lasts about 100% longer. Still, it i don't have battery times like on my old device, but hey... :)

Update 07.03.: SysMon now show me also nearly 100% Cpu usage all the time. i have not installed anything... just dropped a few mp3s and some reboots (i shut the tablet down over night). But for example since 7:00 only 10% battery drain today. if i look via terminal what top says, kworker is "the bad guy" (http://askubuntu.com/questions/33640/kworker-what-is-it-and-why-is-it-hogging-so-much-cpu?answertab=votes#tab-top).

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Sorry guys didn't find this thread before I created mine. I got a report out of perf as instructed by that askubuntu page I found to look into kworker (which I see you've linked too) and it looks like it's something to do with the wireless driver:


Andy Branson ( 2016-04-12 01:07:15 +0300 )edit

answered 2016-05-16 09:58:42 +0300

rinigus gravatar image

updated 2016-05-16 22:58:19 +0300

When you check CPU %, don't forget to check how much CPU was sleeping. You could do it with mcetool (that will give you sleep and total time from boot) or SysMon with CPU sleep monitored (unofficial version available in OpenRepos, https://openrepos.net/content/rinigus/system-monitor-unofficial-edition ; code at https://github.com/rinigus/harbour-systemmonitor ). [Disclosure: I wrote this SysMon extension for CPU sleep when checking out Nexus 4 port].

I would expect that the tablet has a rather large CPU sleep %. Now, as far as I understand, CPU utilization reported the % at the time when tablet is non-suspended, i.e /proc/stat statistics is related to non-sleep time. So, I assume that when your tablet is mostly sleeping and waking up once in a while, it runs housekeeping processes and then goes to sleep as well. This would correlate with high CPU sleep and high CPU utilization %. To get some idea of CPU utilization against the wall clock, try to multiply ( 100 - CPU_sleep_% ) / 100% * CPU_utilization_% .

When you plug in the charger, CPU sleep is disabled. As a result, since the tablet has almost nothing to do, CPU utilization would be very low.

So, that all fits with your case as well as with relatively modest battery consumption.

Now, usually, we see ~10% CPU [corrected the value] utilization in sleep in Nexus 4. It has 4 CPUs and I suspect that its mainly one threaded program doing the housekeeping. In your case, you have 75% CPU usage or higher. Either it means that housekeeping is done on multiple threads or there is something else going on.

When compared to Android tablets, I have Nexus 7 and that can stay idle for a week, no problem. But there is a difference in CPU architecture and many other aspects.

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Thanks for this, your CPU sleep addition to SysMon has helped see what's going on here. These values of ~75% usage would correlate with 3 of the 4 CPUs being suspended, and the other being awake but with low load. Do you think it would be a good idea to subtract CPU sleep from utilization in SysMon?

The suspend success and failure graphs show 'no data' on the tablet. I'll have a look see what's going on there.

Andy Branson ( 2016-05-16 12:43:24 +0300 )edit

Re suspend success/failure: In several ports, file /sys/kernel/debug/suspend_stats contains information regarding suspend stats (see end of https://www.kernel.org/doc/Documentation/power/basic-pm-debugging.txt for example). If you could find where you have this file mounted in the tablet, then please let me know - I'll modify the source accordingly.

Re CPU sleep and utilization: Its seems to create a lot of confusion and I have been confused as well. Perhaps we could extend the utilization graphs by wall clock equivalents.

On the other hand, I'd like to keep current stats as well. Just imagine the case where your device is suspending and having CPU usage low. Such scenario would indicate that it could have suspended more - no point in sitting with low CPU usage and not sleeping :) [unless something else useful is going on]

rinigus ( 2016-05-16 12:56:43 +0300 )edit

It seems identical to the phone:

[root@pootle ~]# cat /sys/kernel/debug/suspend_stats
success: 23384
fail: 2424
failed_freeze: 225
failed_prepare: 0
failed_suspend: 1601
failed_suspend_late: 0
failed_suspend_noirq: 0
failed_resume: 0
failed_resume_early: 0
failed_resume_noirq: 0
  last_failed_dev:      alarmtimer
  last_failed_errno:    -16
  last_failed_step:     suspend

I see your point about the CPU usage display, but I think if the suspend graph is still there then the sleep is being reported well enough. Seeing a high sleep number and low CPU usage graph would possible even let people think their tablet battery is lasting longer :)

Andy Branson ( 2016-05-16 13:09:45 +0300 )edit

Re suspend debug: Indeed, this is identical to what we have on ports. Do you have SFOS Programming API installed? Maybe you could help to debug the issue? The code in question is at


We could also move the discussion regarding this SysMon bug to github, under https://github.com/rinigus/harbour-systemmonitor/ by opening corresponding issue.

rinigus ( 2016-05-16 13:17:12 +0300 )edit

Yes, I've uncommented your debug lines to test. So far I see 'Suspend DATA' in the log, but no 'suspend: ' line after. Will look deeper and create an issue.

Andy Branson ( 2016-05-16 13:38:29 +0300 )edit

answered 2016-02-24 17:15:53 +0300

cgfrost gravatar image

updated 2016-02-24 17:32:18 +0300

Got mine (in the UK) via yoybuy yesterday, they tried to use EMS first and it got sent back at customs in China but then used DHL and no other problems. Came with SF pre-installed and all the original packaging but it's been opened at some point. I also feel bad for going rouge but it's better than not having one. To answer your questions.

  2. Less than 24 hours but it was getting heavy use.
  3. Not sure yet, need to use it more.
  4. 92% at idle, plugging the charger in makes it 1.8%. (Using the same monitoring tool as you).

Something isn't right with the CPU usage me thinks.

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one likely reason for the high CPU usage is that it is scaled back during idle and your monitoring software counts utilisation based on current speed, not maximal speed of the CPU; while on charger, the CPU probably goes full-speed at all times

mornfall ( 2016-02-24 17:37:14 +0300 )edit

Well regarding the CPU usage on the tablet app 'System Monitor' - it was just compiled and uploaded by not the original developer, so there is still the chance that this is a Bug in System Monitor and not optimized at all for the Tablet.

Alex ( 2016-02-24 19:13:22 +0300 )edit

@mornfall, that is actually a very good point. The first rule in doing science is to actually understand how your equipment works...

Moshroom ( 2016-02-24 23:01:50 +0300 )edit

I think you are correct. After a few more days of use it is still consistently showing very high CPU usage when not plugged in but the rate the battery is dropping I expect to get almost a week out of it with only light usage. That would be so if the CPU was maxed out all the time, I haven't noticed it getting hot either.

cgfrost ( 2016-02-26 13:45:15 +0300 )edit

answered 2016-03-02 09:45:30 +0300

lupastro gravatar image

updated 2016-03-02 09:46:37 +0300

Well, this is how the last 8 hours usage report looks like. The tablet was on idle status, because I was sleeping...

image description

That's the performance of the Tablet (in idle mode) between 22:56 yesterday and 6:56 today. I find the WLAN peaks interesting....as well as the constant 93,5% CPU usage.

The battery dropped about 6% in the meantime.

Android Support is not installed. The only apps I installed are "Sysmon", "QuasarMX" and "Sailfish Utilities". Any of them was running during the night.

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answered 2016-03-08 21:52:04 +0300

jaine gravatar image
  2. Not sure yet
  3. Not sure yet, but seems like 1 hour idle -> 1% battery drop
  4. 87.7%

The CPU usage is really interesting...

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answered 2016-03-16 04:27:37 +0300

wkevink gravatar image

hey, i got mine via yoybuy to canada last week. it took about two weeks to ship here.

my answers:

  2. sometimes everyday if i use realy often
  3. 48 h
  4. 85 %
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answered 2016-05-13 23:02:36 +0300

jolladiho gravatar image

original jolla tablet

  2. every day if using it, to often for a tablet
  3. 48h (drains with a rate of round about 1% / h)
  4. 98%

have a test running with some mods it still needs more 12h to run. At the moment the drain is 4% in the first 12h if tablet is idle. More tablet like, but not perfekt and only a workaround.

Let's hope Jolla can fix something with the next update.

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which mode have you done? ;-)

minojolla ( 2018-10-27 11:22:54 +0300 )edit

I wrote a script that puts the last 2 cpu's offline if the screen turns off and sets the powersave mode via mcetool. That slows down the consumption a little bit.

echo "0" > /sys/devices/system/cpu/cpu2/online
echo "0" > /sys/devices/system/cpu/cpu3/online
mcetool -F enabled
jolladiho ( 2018-10-27 20:23:32 +0300 )edit

Seem a brillant idea. I can try applying theese 3 lines via Terminal? I am testing a Jolla 'Aigo' Tablet, but I noticed this big issue. Is it possible that Jolla forget about a similar issue, in a tablet?

minojolla ( 2018-10-27 21:31:43 +0300 )edit

The idea was better then the power management of the tablet.

Yes, that are terminal commands. You need root permissions, you do it by your own risk and you know what you are doing.

Nobody cares that tablet any more, because it and its adaptation are a products of a failed project.

jolladiho ( 2018-10-28 12:28:56 +0300 )edit

Ok so basically It became devel-su password echo "0" > /sys/devices/system/cpu/cpu2/online echo "0" > /sys/devices/system/cpu/cpu3/online mcetool -F enabled

But where the instruction states the 'display off' condition? And, there is an undo command line?

minojolla ( 2018-10-28 14:45:10 +0300 )edit

answered 2016-05-15 20:38:46 +0300

shfit gravatar image

updated 2016-05-16 01:24:36 +0300

original jolla tablet

1) 2) every day 3) from 25% to 20% in about 4h when idle in airplane mode with screen off and system monitor running 4) about 6% when connected to charger, about 75% when disconnected.

there is something wierd going on. some system process seems to be hogging cpu while the tablet is idle and disconnected from the carger. i inspected it briefly with top and all i could see was that a kworker and lipstick were using cpu, but i havent investigated it n detail.

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Asked: 2016-02-24 13:22:41 +0300

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Last updated: May 16 '16