I/O Subsystem - HP ML530 - ProLiant - 128 MB RAM Brief Manual

ProLiant ML530 High-Performance Technologies

I/O subsystem

In addition to the requested data, the controllers retrieve data from subsequent sequential
memory addresses on both DIMMs in anticipation of future data requests. The retrieved
blocks of data are merged together in 128-bit lines on the memory bus. The data is sent
to the processor's L2 cache as four 128-bit lines (512 bits) to match the cache line size
in the Intel Xeon Processor. The data rate on the memory bus matches the data rate on
the quad-pumped processor bus (3.2 GB/s), which reduces latency in memory reads
and writes.
figure 9. memory read using interleaving
What are the software application performance benefits of memory interleaving? Dual-
interleaved memory fills the processor cache faster than standard, non-interleaved
memory systems so that the processors can execute applications faster. This synergy
between the processor and memory subsystems boosts the overall system performance of
the ProLiant ML530 G2 server well beyond that of 2P servers without Hyper-Threading
technology and two-way memory interleaving.
The ServerWorks Grand Champion HE chipset ensures that the bandwidth of the I/O
subsystem complements the processor and memory bandwidths (see Figure 10). The
chipset supports three 400-MHz (double-pumped 200-MHz clock) Inter Module (IM)
Buses. Two 32-bit IM Buses are used to provide 3.2 GB/s (1.6 GB/s each) to two PCI-X
bridges. Each PCI-X bridge controls two 800-MB/s (100-MHz, 64-bit) PCI-X buses. A
maximum of two PCI-X slots per bus are used for better load balancing of I/O resources,
such as array controllers and network interconnect controllers (NICs). Four of the seven
PCI-X slots support hot-plug operation. The OSs that support PCI-X hot-plug operation
include Windows 2000 Server products, Netware 4.2 and higher, and SCO UNIX.
PCI-X provides full backward compatibility with PCI 2.2 hardware and software, thereby
preserving customer investments as I/O technology continues to evolve.
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