[Bugs] #2141 UNSP: Memory and CPU status indicator for the frame.

[Sugar Labs Bugs]

#2141: Memory and CPU status indicator for the frame.
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    Reporter:  m_anish                    |          Owner:  tomeu                      
        Type:  enhancement                |         Status:  new                        
    Priority:  Unspecified by Maintainer  |      Milestone:  Unspecified by Release Team
   Component:  sugar                      |        Version:  Unspecified                
    Severity:  Unspecified                |       Keywords:  r? dextrose                
Distribution:  Unspecified                |   Status_field:  Unconfirmed                
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Changes (by m_anish):

  * keywords:  r! dextrose => r? dextrose


Comment:

 Replying to [comment:4 tomeu]:
 > Replying to [comment:3 m_anish]:
 > > Replying to [comment:2 tomeu]:
 > >
 > > Thanks for the review.
 > >
 > > > > +        self.create_palette()
 > > >
 > > > Why create the palette at this point?
 > >
 > > The system resources are computed at 5 second intervals. So, if I
 create the palette when the frame is invoked and attempt to view the the
 resource icon's palette immediately, I'll see a palette with two empty
 progress-bars and no text for a few seconds. Note that this will happen
 only for the first time when viewing the frame icon's palette.
 > >
 > > To overcome this, I create the palette early. So as soon as I attempt
 to view it for the first time, I won't see empty info as in the case above
 >
 > Maybe I'm missing something: why not compute the data when the palette
 is first displayed, then update it every 5 seconds until the palette is
 closed?


 There are two reasons for this

 ==Reason 1==

 Its because of the way the resource usage numbers are acquired. Memory
 usage can be computed instantaneously by reading /proc/meminfo.

 However, CPU usage cannot be computed instantaneously. It is computed by
 finding the difference in /proc/stat numbers between two snapshots (which,
 in this case are 5 seconds apart). Thus, if I were to start my CPU usage
 computation the moment the palette is made visible, something like this
 would happen:

 1) Palette invoked/made visible

 2.a) Compute memory usage
 2.b) Start computing CPU usage -> take initial /proc/stat snapshot

 ... 5 seconds later ...

 3) Take 2nd /proc/stat snapshot. From difference between two snapshots,
 compute CPU usage
 4) Update palette with CPU and memory usage numbers (Until this time, the
 palette would display two empty progress bars)

 Note: This problem of an 'empty' palette will happen only for the very
 first time when viewing the palette. Every subsequent time, the palette
 would contain meaningful data whenever visible.

 ==Reason 2==

 Also, unlike the previous versions of this patch, I am dynamically
 changing the frame icon based on current available resources. This way, a
 user can simply make the frame visible and get an abstract idea of system
 resources just by looking at the icon which would either be normal, happy
 or sad (or error when an exception happens), much like visual feedback the
 speaker or network icons provide. It is another reason why I cannot limit
 my resource-usage computation to the palette-is-visible time window.

-- 
Ticket URL: <http://bugs.sugarlabs.org/ticket/2141#comment:5>
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