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QuickSpecs
Configuration
DIMMs alternates among the four subsystems. This rule provides maximum memory bandwidth
on the cell, by equally populating all four memory subsystems.
23
All cells in a partition should have the same number of processors.
24
The number of active processors per cell should be balanced across the partition, however
minor differences are OK. (Example: 4 active processors on one cell and three active
processors on the second cell)
25
If memory is going to be configured as fully interleaved, all cells in a partition should have the
same amount of memory (symmetric memory loading). Asymmetrically distributed memory
affects the interleaving of cache lines across the cells. Asymmetrically distributed memory can
create memory regions that are non optimally interleaved. Applications whose memory pages
land in memory interleaved across just one cell can see up to 16 times less bandwidth than
ones whose pages are interleaved across all cells.
26
If a partition contains 4 or fewer cells, all the cells should be linked to the same crossbar (quad)
in order to eliminate bottlenecks and the sharing of crossbar bandwidth with other partitions. In
each Superdome cabinet, slots 0, 1, 2 and 3 link to the same crossbar and slots 4, 5, 6 and 7
link to the same crossbar.
27
A Core I/O card should not be selected as the main network interface to a partition. A Core
I/O card is a PCI 1X card that possibly produces lower performance than a comparable PCI X
66 MHz card. (sx1000 only)
28
The number of cells in a partition should be a power of two, i.e., 2, 4, 8, or 16.
Optimal interleaving of memory across cells requires that the number of cells be a power of
two. Building a partition that does not meet this requirement can create memory regions that
are non optimally interleaved. Applications whose memory pages land in the memory that is
interleaved across just one cell can experience up to 16 times less bandwidth than pages which
are interleaved across all 16 cells.
29
Before consolidating partitions in a Superdome 32 processor or 64 processor system, the
following link load calculation should be performed for each link between crossbars in the
proposed partition.
Links loads less then 1 are best. As the link load begins to approach 2 performance bottlenecks
may occur.
For crossbars X and Y
Link Load = Qx * Qy / Qt / L, where
- Qx is the number of cells connected to crossbar X (quad)
- Qy is the number of cells connected to crossbar Y (quad)
- Qt is the total number of cells in the partition
- L is the number of links between crossbar X and Y (2 for Superdome 32 processor systems
and 1 for Superdome 64 processor systems)
30
Maximum performance for optimal configurations (power of two cells, uniform memory across
cells, power of two DIMM ranks per cell)
31
(If rule #30 cannot be met, rule #31 is recommended) Non-power of two cells, but still
uniform memory across cells, power of two DIMM ranks per cell, uniform type of DIMM.
32
(If rule #30 or #31 cannot be met, rule #32 is recommended) Same amount of memory in
each cell, but possibly different memory types in each cell (for instance, a two cell configuration
with 8 512MB DIMMs (sx1000 only) in one cell, and 4 1GB DIMMs in the other). Differences
in memory across different cells within the same partition should be minimal for the best
performance.
DA - 11717
Worldwide — Version 57 — October 23, 2009
HP Integrity Superdome Servers 16- processor, 32-
HP Integrity Superdome Servers 16- processor, 32-
HP Integrity Superdome Servers 16- processor, 32-
HP Integrity Superdome Servers 16- processor, 32-
processor, and 64- processor Systems
processor, and 64- processor Systems
processor, and 64- processor Systems
processor, and 64- processor Systems
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