Dell PowerEdge R820 - Manual (Page 13)

Performance Analysis of HPC Applications on Several Dell PowerEdge 12 th Generation Servers
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that have four memory channels, the total memory bandwidth is ~22 percent lower and the memory
bandwidth per core is ~25 percent lower than the PowerEdge R620.
Memory bandwidth Figure 4.
* BIOS options: System Profile is set to Max Performance and C states and C1E are disabled.
4.2. HPL
Moving on to the application level performance, High performance Linpack (HPL), a popular
computationally intensive application is analyzed first. The problem size used for all the runs is
maintained at 90 percent of the entire memory as described in Table 3. Note that this translates to
different problem sizes (values of “N”) for each configuration.
The results are plotted in Figure 5. From the figure it is clear that the Dell PowerEdge M620 and the
PowerEdge R820 perform similarly when comparing the same number of cores. This performance is
attributed to the similar core frequency and memory frequency of these two configurations. Clearly
HPL is not affected by the difference in memory bandwidth at these core counts. HPL also scales well
and the interconnect is not a bottleneck at these core counts. This is apparent from the graph because
the number of PowerEdge R820 servers needed to achieve a certain core count is half that of the
PowerEdge M620 servers, but the performance of both clusters is similar.
The PowerEdge M420s perform consistently lower than the M620s by ~15 to 19 percent irrespective of
core count. The difference in core frequency between the PowerEdge M420 (2.3 GHz) and the
PowerEdge M620 (2.7 GHz) is 15 percent. The PowerEdge M420 also has a lower total memory
configuration, and uses InfiniBand FDR10, which is slower than the InfiniBand FDR used in the
PowerEdge M620s. This explains the consistent lower performance of the PowerEdge M420s.
4.8 GB/s/core
3.4 GB/s/core
3.7GB/s/core
0
20
40
60
80
100
120
Tota
l Mem
or
y
b
and
wi
d
th
(GB
/s
)
R620 R820 M420