#3096 HIGH Trial-3: zooming to home view no longer zooms, seems to block

[Zarro Boogs per Child]

#3096: zooming to home view no longer zooms, seems to block
---------------------+------------------------------------------------------
  Reporter:  J5      |       Owner:  danw   
      Type:  defect  |      Status:  new    
  Priority:  high    |   Milestone:  Trial-3
 Component:  sugar   |     Version:         
Resolution:          |    Keywords:  review?
  Verified:  0       |  
---------------------+------------------------------------------------------
Changes (by danw):

 * cc: marco (added)
  * keywords:  performance => review?


Comment:

 Attached patch makes a few changes:

 1. Makes sure we don't run _update_activity_sizes twice in a row (which
 was happening before).
 2. Only gets the shell mappings once rather than every time we
 _update_activity_sizes
 3. Rewrite the proc_smaps code to be faster, and avoid parsing the bits we
 don't care about here.

 This seems to make it fast enough to bring the animation back, although it
 still is a little jumpy compared to the other transitions.

 Making it any faster would be tricky: it's not doing any extra work (it
 only reads the /proc/PID/smaps for the activity processes, not any other
 processes, and it only reads each of them once per calculation). The
 problem is just that /proc/PID/smaps is gigantic for a sugar-based process
 because of all of the shared libraries it imports.

 From previous discussions, I'm pretty sure Eben wants to have the ring
 show the correct sizes immediately upon switching into the home view, so
 *not* blocking is not a great solution (although we could try to rearrange
 it to do the animation and the size calculation in parallel).

 Another possibility would be to write the size calculation code in C, or
 even make the kernel compute the sizes for us (via a different file in
 /proc/PID). (That could possibly tie into OOM-killer work?)

-- 
Ticket URL: <https://dev.laptop.org/ticket/3096#comment:6>
One Laptop Per Child <https://dev.laptop.org>
OLPC bug tracking system