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 X 1X card that possibly produces lower performance than a comparable PCI
X 2X card.
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-socket or 64-socket 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-socket systems and 1
for Superdome 64-socket 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 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.
33
Same amount of memory in each cell, but non optimal and/or mixed loading within a cell (for
instance, a two cell configuration with 16 512MB DIMMs and 8 1GB DIMMs in each cell).
34
Non-uniform amount of memory across cells (this needs to boot and run, but performance is
whatever you get).
35
For the same amount of total memory, best performance is with a larger number of smaller size
DIMMs.
QuickSpecs
HP Integrity Superdome Servers 16-socket, 32-socket,
HP Integrity Superdome Servers 16-socket, 32-socket,
HP Integrity Superdome Servers 16-socket, 32-socket,
HP Integrity Superdome Servers 16-socket, 32-socket,
and 64-socket
and 64-socket
and 64-socket
and 64-socket
Configuration
DA - 11717 Worldwide — Version 20 — May 3, 2005
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