Java Reference
In-Depth Information
Table 6-4. Tunings enabled with AggressiveHeap
Flag
Value
The minimum of half of all memory, or all memory: 160 MB
Xmx
The same as Xmx
Xms
3/8ths of whatever was set as Xmx
NewSize
UseLargePages
true
ResizeTLAB
false
256 KB
TLABSize
UseParallelGC
true
Same as current default
ParallelGCThreads
256 KB (default is 4 KB)
YoungPLABSize
8 KB (default is 1 KB)
OldPLABSize
CompilationPolicyChoice 0 (the current default)
100 (default is 10)
ThresholdTolerance
false (default is true )
ScavengeBeforeFullGC
BindGCTaskThreadsToCPUs true (default is false )
Those last six flags are obscure enough that I have not discussed them elsewhere in this
topic. Briefly, they cover these areas:
PLAB sizing
PLABs are promotion-local allocation buffers—these are per-thread regions used during
scavenging the generations in a GC. Each thread can promote into a specific PLAB, neg-
ating the need for synchronization (analogous to the way TLABs work).
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