IBM Power 750 - Memory Bandwidth

60 IBM Power 750 and 760 Technical Overview and Introduction
2.3.3 Memory bandwidth
POWER7+ has exceptional cache, memory, and interconnect bandwidths. Table 2-8 shows
the maximum bandwidth estimate for the Power 750 system running at 4.06 GHz.
Table 2-8 Power 750 processor and memory bandwidth estimates
Table 2-9 shows the maximum bandwidth estimate for a Power 760 running at 3.416 GHz.
Table 2-9 Power 760 processor and memory bandwidth estimates
The bandwidth figures for the caches are calculated as follows:
򐂰 L1 cache: In one clock cycle, two 16-byte load operations and one 16-byte store operation
can be accomplished. Using an 4.060 GHz processor card the formula is as follows:
(2 * 16 B + 1 * 16 B) * 4.060 GHz = 194.88 GBps
򐂰 L2 cache: In one clock cycle, one 32-byte load operation and one 16-byte store operation
can be accomplished. Using an 4.060 GHz processor card the formula is as follows:
(1 * 32 B + 1 * 16 B) * 4.060 GHz = 194.88 GBps
򐂰 L3 cache: One 32-byte load operation and one 32-byte store operation can be
accomplished at half-clock speed. Using an 4.060 GHz processor card, the formula is as
follows:
(1 * 32 B + 1 * 32 B) * (4.060 GHz / 2) = 129.92 GBps
Memory Power 750
4.060 GHz processor card
L1 (data) cache 194.880 GBps
L2 cache 194.880 GBps
L3 cache 129.920 GBps
򐂰 Chip to chip in DCM (XZ bus)
򐂰 4 DCMs
򐂰 96.768 GBps
򐂰 387.072 GBps
DCM to DCM (AB bus) 236.544 GBps
򐂰 System memory
򐂰 4 DCMs
򐂰 68.224 GBps
򐂰 272.896 GBps
Memory Power 760
3.416 GHz processor card
L1 (data) cache 163.968 GBps
L2 cache 163.968 GBps
L3 cache 109.312 GBps
򐂰 Chip to chip in DCM (XZ bus)
򐂰 4 DCMs
96.768 GBps
387.072 GBps
DCM to DCM (AB bus) 236.544 GBps
򐂰 System memory
򐂰 4 DCMs
68.224 GBps
272.896 GBps