Hyper-Threading Technology, New Feature of Intel Xeon Processor White Paper
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167T-0202A-WWEN
Analysis
The Montecarlo application is multi-tasked as well as computationally intensive. A task could
utilize all of the processor resources, which is determined by the fact that the ratio between the
physical 1P (30.1) and physical 2P (15.15) is almost 2:1. Independent of the 1P or 2P case,
Hyper-Threading technology does not yield any performance gain since the benchmark is
resource bound. See Figure 15.
Montecarlo Benchmark on Windows XP
30.10
15.15
30.27
15.00
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
Lowe
r is
be
tt
e
r
Enable
30.10
15.15
Disable
30.27
15.00
1P
2P
Figure 15:
Verilog Compiled Simulation Benchmark
The Verilog Compiled Simulation (VCS) benchmark script includes four independent tasks that
run at the same time. Each task simulates the same reset sequence of a memory controller. The
VCS benchmark is very memory intensive.
Analysis
This VCS application is multi-tasked as well as memory intensive. A task requires about 20MB
of data for simulation. The data cache is shared between the two threads, which results in frequent
cache line replacement and hence shows poor performance when Hyper-Threading is enabled. In
a two physical processor case with Hyper threading disabled, with cache available on each
processor, there is a significant improvement in performance. With Hyper-Threading technology
enabled in a dual processor configuration, the performance is worse than just a true dual
processor configuration. This poor result is due to the sharing of resources between the same
processor and checking the other processor’s cache validity for correct data. See Figure 16.
