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ESUG 2011, Edinburgh
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VisualWorks Object Memory Management
Andrés Valloud
Structure
Eden
SASB
Eden
Old
SASB
Eden
SASB
Eden
Perm
Old
Evolution
Instance creation
Scavenge 1
Scavenge 2
Scavenge 3
Scavenge 4
Tenured
IGC / GC
Perm save
Global GC
RIP
But, speaking of GC...
SASB
Eden
Perm
Old
Perm
OldRT
SASB
EdenScavenge finds
live objects faster
OldRT
PermOldRT
SASB
EdenScavenge finds
live objects faster
IGC / GC find live objects
faster
Responsibilities
OldRT
PermOldRT
SASB
Eden
OldRT
PermOldRT
SASB
EdenVM scavenges
new space
OldRT
PermOldRT
SASB
EdenVM scavenges
new spaceVI must ensure
success
OldRT
PermOldRT
SASB
EdenVM scavenges
new spaceVI must ensure
success
VM signals low memory
semaphore
OldRT
PermOldRT
SASB
EdenVM scavenges
new spaceVI must ensure
success
VI manages old space (GC,
grow, shrink)
VM signals low memory
semaphore
OldRT
PermOldRT
SASB
EdenVM scavenges
new spaceVI must ensure
success
VI manages old space (GC,
grow, shrink)
VM signals low memory
semaphore
VM (few) fixed actions
VI memory policy classes
Memory policies
OldRT
PermOldRT
SASB
EdenWorst case scavenge
OldRT
PermOldRT
SASB
EdenEden and
SA or SB fullWorst case scavenge
OldRT
PermOldRT
SASB
EdenEden and
SA or SB full
RT grows
Worst case scavenge
OldRT
PermOldRT
SASB
EdenEden and
SA or SB full
RT grows
Old RT grows
Worst case scavenge
OldRT
PermOldRT
SASB
EdenEden and
SA or SB full
RT grows
Old RT grows
Stack
Stack zone full, flushed to
object memory
Worst case scavenge
due to GC
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
The picture
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
The pictureGrowth
Increments
Improvements since VisualWorks 7.7
ObjectMemory>>igcState...aborting ifTrue: [^#aborting]....
MemoryPolicy>>dealWithIGC...memoryStatus igcState = #aborted
ifTrue: [“recover from IGC abort”]....
Fixed since VW 7.7
Fixed since VW 7.7
IGC does not recover from
stack overflow
ObjectMemory>>igcState...aborting ifTrue: [^#aborting]....
MemoryPolicy>>dealWithIGC...memoryStatus igcState = #aborted
ifTrue: [“recover from IGC abort”]....
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7IGC as last
resort, bogus emergencies
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7VM crash dueto scavenge
failure
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7Too low for
modernapplications
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7
GrowthIncrements
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7Tiny growthincrement,
excessive GC
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7Tiny growthincrement,
fragmentation
0Upper
Memory Bound
ImageSize
GrowthRegimeBound
EmergencyThreshold
Worst CaseScavenge
Fixed since VW 7.7Low free
memory limit, even more GC
New technology
New technologyTESTS
New technologyTESTS
•MemoryPolicyChecker
New technologyTESTS
•MemoryPolicyChecker
•MemoryPolicyTuner
New technologyTESTS
•MemoryPolicyChecker
•MemoryPolicyTuner
•MemoryPolicyStressTest
Before and after
Before
After
0Upper
Memory Bound
0Upper
Memory Bound
0
10,000
20,000
30,000
40,000
A (x100) B (x100) C (x400) D (x40) E (x40) F (x6) G (x6)
Run time per stress test case, in seconds
VW 7.7 legacy MemoryPolicy (with fixes) ~1 day, if they workVW 7.7.1 without sizesAtStartup tuning ~160 minutesVW 7.7.1 default ~73 minutes
A: pointer garbageB: byte garbageC: point creation
Segmented containerD: byte allocationE: pointer allocation
Large containerF: byte allocationG: pointer allocation
Print 2 web, ESUG 2009
Print 2 web, ESUG 2009
2.5x faster(with small
changes only)
X
VisualWorks 7.8and beyond
VisualWorks 7.8+
•Fixed space allocation fixed
•Improved weak / ephemeron support
•IGC performance improvements
•GC / IGC mark stack overflow prevention
•GC moves large objects back into large space
•New -m[1..7] VM switches
VisualWorks 7.8+
•Fixed space allocation fixed
•Improved weak / ephemeron support
•IGC performance improvements
•GC / IGC mark stack overflow prevention
•GC moves large objects back into large space
•New -m[1..7] VM switches
DONE
VisualWorks 7.9
VisualWorks 7.9
•Up to 40% faster GC
VisualWorks 7.9
•Up to 40% faster GC
•Improved IGC uses less memory
VisualWorks 7.9
•Up to 40% faster GC
•Improved IGC uses less memory
•Adaptive time based memory policy IGC driver
VisualWorks 7.9
•Up to 40% faster GC
•Improved IGC uses less memory
•Adaptive time based memory policy IGC driver
•Memory policy IGC smart abort
VisualWorks 7.9
•Up to 40% faster GC
•Improved IGC uses less memory
•Adaptive time based memory policy IGC driver
•Memory policy IGC smart abort
•Memory policy IGC switch
VisualWorks 7.9
•Up to 40% faster GC
•Improved IGC uses less memory
•Adaptive time based memory policy IGC driver
•Memory policy IGC smart abort
•Memory policy IGC switch
•Updates to the OldRT, become:, fixed space...
•Up to 40% faster GC
•Improved IGC uses less memory
•Adaptive time based memory policy IGC driver
•Memory policy IGC smart abort
•Memory policy IGC switch
•Updates to the OldRT, become:, fixed space...
VisualWorks 7.9
DONE
Questions?
