Practical resource management for mobile devices: Pooling is magic Методики, трюки и оптимизацию при управлении ресурсами игры. Как перестать беспокоится и начать эффективно использовать память.

1. PRACTICAL RESOURCE MANAGEMENT FOR MOBILE DEVICES
POOLING IS MAGIC

2. W H AT D O W E K N O W A B O U T M O B I L E

3. W H AT D O W E K N O W A B O U T M O B I L E
• Battery is limited

4. W H AT D O W E K N O W A B O U T M O B I L E
• Battery is limited
• Processing power is limited

5. W H AT D O W E K N O W A B O U T M O B I L E
• Battery is limited
• Processing power is limited
• Storage is limited

6. W H AT D O W E K N O W A B O U T M O B I L E
• Battery is limited
• Processing power is limited
• Storage is limited
• RAM is limited

7. W H AT D O W E K N O W A B O U T M O B I L E
• Battery is limited
• Processing power is limited
• Storage is limited
• RAM is limited
• Ubiquitous

8. W H AT D O W E K N O W A B O U T G A M E S

9. W H AT D O W E K N O W A B O U T G A M E S
• Consume all of the CPU

10. W H AT D O W E K N O W A B O U T G A M E S
• Consume all of the CPU
• Consume all of the GPU

11. W H AT D O W E K N O W A B O U T G A M E S
• Consume all of the CPU
• Consume all of the GPU
• Can consume a lot of storage space

12. W H AT D O W E K N O W A B O U T G A M E S
• Consume all of the CPU
• Consume all of the GPU
• Can consume a lot of storage space
• Consume all of RAM

13. W H AT D O W E K N O W A B O U T G A M E S
• Consume all of the CPU
• Consume all of the GPU
• Can consume a lot of storage space
• Consume all of RAM
• Thats what people do on mobile

15. R E D U C E B AT T E R Y C O N S U M P T I O N
• Reduce your network activity
• Every time cell radio is activated for 20-30 seconds
• Batch requests
• Prefetch as much data as possible
• Maximize bandwidth usage
• Reduce storage activity
• Don’t keep threads busy for no reason

16. R E D U C E A P P L I C AT I O N S I Z E
• Different assets for different device categories
• Use a smaller runtime if available
• Use texture atlases
• Enable batch drawing
• Less memory
• Use compressed textures where possible
• Use WebP for uncompressed images

17. GAMES ARE DIFFERENT

18. GAMES ARE DIFFERENT
• A lot is known in advance:
• Usage patterns are known
• Data dependencies are known
• Asset restrictions are known

19. USE YOUR KNOWLEDGE

20. USE YOUR KNOWLEDGE
• Set restrictions for designers and artists
• Custom build process:
• Use available tools
• Write your own

21. M E M O R Y A L L O C AT I O N PAT T E R S
• Application scope (allocated at app start, freed on
shutdown)
• Level scope (allocated at level start, freed on level
end)
• Frame scope (allocated for one frame, sometimes for
two)
• Temporary allocations

22. M E M O R Y A L L O C AT I O N PAT T E R N S
• Grab all required memory once on app start - this is all
you will have
• Divide it between several heaps for different
subsystems (avoids fragmentation, decoupling)
• Use stack allocations where possible (alloca, structs,
static arrays)

23. G O T TA G O F A S T
• Linear allocator:
• Just increase the pointer and adjust for alignment
• As fast as it can get
• Free all memory at once (reset pointer)

24. L I N E A R A L L O C AT O R
• Can only free in reverse order (better free all at once at scope
exit)
• How do we deal with temporary allocations?
• Separate heap for temporaries?
• Nope! Double-ended linear allocator
• What about cleanup?
• Scope stack (http://dice.se/publications/scope-stack-
allocation/)

25. B U T W A I T, W H AT A B O U T
• Objects with undefined lifetime:
• Use object pools
• Objects with variable size:
• Custom allocator (several free-lists for different sizes)

26. OBJECT POOLS
• Preallocate certain number of objects of same type
• Use objects from pool whenever one needs an object of that
type
• Return objects to pool when done (resource released,
reference count is zero)
• Can process all the pool in one go
• Better cache efficiency
• Set restrictions on object count

27. OBJECT POOLS
• Particle systems
• Components
• Game entities
• Sounds
• etc.

28. RESOURCE LIFETIME
• Use registers for resources of same type (fonts,
textures, etc.)
• Use reference counters only as last resort:
• Thrash CPU cache
• Unnecessary work
• Unbounded pauses on deallocation cascades

29. RESOURCE LIFETIME
• Don’t leave some resource hanging if it will be reused
in some other level
• Usually its ok to unload and load stuff again to avoid
heap fragmentation

30. REDUCE MEMORY USAGE
• ‘Prototype’ pattern:
• Extract some part to be shared by all objects
• Usually used as a template for creating stuff
• Best allocation is no allocation at all

31. ‘ P R O T O T Y P E ’ PAT T E R N
• Animations
• Game entities (Similar to prefabs in Unity)
• Anything that could share an immutable part between
instances

32. REDUCE MEMORY USAGE
• Unity:
• Use value types (structs, primitive types)
• Avoid boxing/unboxing
• Don’t use default GUI
• Reuse buffers and objects where possible

33. • Always base your decisions on data
• USE PROFILER
• Don’t use this rules as a dogma, think for yourself

34. S TA R T P R E A L L O C AT I N G
AND
STOP WORRYING

35. QUESTIONS?
M A X K LY G A
E M A I L : M A X . K LY G A @ G M A I L . C O M
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