ccNUMA Overview

Comparison of existing HP 9000 high-end SMP servers to the new
HP Integrity SMP servers
The primary physical difference between the old and current high-end SMP servers from HP is the improvement of
the cell memory bandwidth. The primary logical difference between the two systems is the segregation of memory
into local memory and interleave memory, as shown in Figure 3.
Figure 3. HP Integrity server memory logical diagram
Table 1. Comparison of generations of HP Superdome servers
HP 9000 Superdome HP Integrity Server
Bandwidth (sustained)
CPU buses/cell 5.2 GB/s 10.8 GB/s
I/O/cell (avg. mix) 1.0 GB/s 1.2 GB/s
Memory/cell 3.2 GB/s 7.2 GB/s
Crossbar/cell 5.2 GB/s 6.4 GB/s
Latency (load-to-use)
Local memory 212 ns 243 ns
1-hop memory 302 ns 423 ns
2-hop memory 366 ns 479 ns
Cache-to-cache 4 hop 4 hop
Cache-line size 64 bytes 128 bytes
The HP 9000 Superdome memory system bandwidth is balanced between local and remote performance in a
proportion that makes treating the memory system as physically uniform a useful simplification. The HP Integrity
server increases memory bandwidth in all respects compared to the HP 9000 Superdome. Memory bandwidth to
the processors is doubled, and bandwidth from the local memory system is more than doubled. Crossbar
bandwidth increases by 25%, and I/O bandwidth increases by 20%. Since the local memory bandwidth
increases much more in proportion to the crossbar bandwidth, the HP Integrity server exhibits stronger ccNUMA
behavior.
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