IBM I5 Server User Manual


 
iSeries. mySeries.
Main Storage Concepts
Memory Allocation Facts
A “Hardware Page Table (HPT)” is needed to manage memory
Power4 Hypervisor reserved HPT within partition memory
Power5 Hypervisor allocates HPT separately from partition memory
Size of the HPT depends of the maximum memory amount the partition can receive
Basic calculation : maximum memory divided by 64, rounded up to next power of 2
A partition can allocates a maximum of 12 GB (12288 MB)
HPT size will be 12288 / 64 = 192 ... next power of 2 is ... 256
HPT size will be 256 MB
Recommendation
Take care of HPT when allocating memory to partitions !
Plan to allocate 12288 - 256 = 12032 MB for the partition
Memory actually used will be 12288 MB
Main Storage size MUST be carefully planned !
37
iSeries. mySeries.
Main Storage Concepts
Memory Allocation Facts
Remember
A node is a packaged set of processors, caches (L1+L2+L3) and memory on a module
Remember about ... “home node”, “local node” and “remote node” ?
Remember about ... “local memory access” and “remote memory access”
Remember about ... “memory affinity” ?
!"#$
@ABC
@ABD
@ABC
@ABD
@ABC
@ABD
@ABC
@ABD
!,64’>1$%,9"
+D
+E
+D
+E
+D
+E
+D
+E
!"#$
@ABC
@ABD
@ABC
@ABD
@ABC
@ABD
@ABC
@ABD
!,64’>1$%,9"
+D
+E
+D
+E
+D
+E
+D
+E
38