ubuntu-phone team mailing list archive

[Colin Ian King <colin.king@xxxxxxxxxxxxx>]

On 05/09/13 14:39, Thomas Voß wrote:
> On Thu, Sep 5, 2013 at 3:25 PM, Joe Talbott <joe.talbott@xxxxxxxxxxxxx> wrote:
>> On Thu, Sep 05, 2013 at 03:01:37PM +0300, Alberto Mardegan wrote:
>>> On 09/05/2013 12:42 PM, Colin Ian King wrote:
>>>> On 05/09/13 10:33, Colin Ian King wrote:
>>>>> On 05/09/13 10:23, Evan Dandrea wrote:
>>>>>> Stuart Langridge brought up an interesting idea for this on IRC, which
>>>>>> I'm copying here rather than having more side discussions:
>>> [...]
>>>
>>> Oops, I should have read the whole thread before posting my previous
>>> e-mail. :-)
>>>
>>>> Anyhow, I still think myAppIsRunning() is open to abuse as it will in
>>>> time be lavishly added to all sorts of tight loops that suck CPU, which
>>>> just adds more overhead on the long run.
>>>
>>> Well, if we don't have a myAppIsRunning() API, apps can simply busy-loop
>>> whenever they want, so I don't see much harm in adding this API.
>>> We could also protect it with apparmor, so that the usage of this API
>>> must be explicitly declared in the application's manifest file (and then
>>> we could question whether the app has any reason to use it).
>>>
>>> Note however that this would still solve the issue of detecting apps who
>>> use too much CPU time because of some bugs, which I think was the
>>> original goal.
>>
>> Would a watchdog sort of timer work better here?  One where the OS sends
>> a signal to a high CPU usage app and if the app doesn't respond to the
>> signal we have a better clue that something is amiss.
>>
> 
> Hmmm, effectively extending the ANR approach to non-UI bits. That is
> interesting idea. Admittedly, an app could work around that, too, but
> hey :) Further extending on the idea: Whenever we identify a process
> that is using too much CPU over a certain period of time, we start
> ptrac'ing it and send over a SIGXCPU. If the process hasn't setup a
> signal handler for that signal and we find out (waitpid and friends),
> we can assume that the process is either not behaving in the Ubuntu
> way _or_ something is wrong and we SIGKILL. Alternatively, we could
> use SIGUSR1/SIGUSR2.
> 
> Makes sense?

Thinking a bit laterally here, when my HDD or SSD fills up on my desktop
I get a pop-up message warning me so that I can deal with the low
storage issue.  CPU is the same, if it is being abused then perhaps we
need to alert the user. Maybe a pop-up to say that a process is
misbehaving and if it's not handled then we kill the rouge process.

> 
>   Thomas
> 
>> Thanks,
>> Joe
>>
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