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Comparing Sandy Bridge vs. Ivy Bridge processors for HPC applications

Mayura Deshmukh - Dell, PSP team - NCSA, May 2014

As new server technologies become available, each generation is touted as being better, faster,

more efficient, and laden with new features. For an HPC user, the question is “how much better?”,

“how much faster?” and especially, “how much does it benefit my specific application?”

For nearly 30 years, the National Center for Supercomputing Applications (NCSA) has been a

leading site for some of the world’s most advanced computing and data systems. NCSA’s Private

Sector Program (PSP) is also the largest industry engagement effort at an HPC center in America,

providing computing, data, and other resources to help companies leverage supercomputing to

solve the most challenging science and engineering problems.

This blog presents some of the work conducted by NCSA’s PSP to measure and analyze the

performance benefits of the new Intel Xeon E5-2600 v2 processors (code-named Ivy Bridge) over

the previous generation E5-2600 series (code-named Sandy Bridge). The focus here is on various

HPC applications widely-used by researchers and designers in the manufacturing sector. A mix of

commercial and open source applications like ANSYS Fluent, LS-DYNA, Simulia Abaqus, MUMPS,

and LAMMPS were selected for this investigation. High-Performance Linpack (HPL) benchmark

results are also presented.

The main difference between the two processor generations under study is the shrinking of process

technology from 32nm to 22nm. This allows fitting more transistors on the chip, higher clock rates,

and better power management. For example, running the SPEC power benchmark with 100% load

on Dell Power Edge R720 with Ivy Bridge (IVB) Intel Xeon E5-2660 v2 showed 25% lower peak

CPU power consumption compared to HUAWEI Tecal RH2288 V2 server with Sandy Bridge (SB)

Xeon E5 2660. A 2.0 GHz SB processor runs at max TDP of 60W whereas a 2.0 GHz IVB processor

runs at max TDP 50W. Also for processors with maximum TDP 150W the clock speed of IVB (3.4

GHz) is higher than that of SB processors (3.1 GHz). It is essential for users to understand the power

and frequency differences between the two generations before selecting a processor for their

application. Both processors have an integrated memory controller that supports four DDR3

channels. SB processors support memory speeds up to 1600 MT/s, whereas IVB support memory

speeds up to 1866 MT/s.

When selecting a CPU for your application it is important to consider factors like power

consumption, usable bandwidth (for applications on multiple nodes) along with the clock speed

and the number of cores.

Table 1 gives more information about the application and the hardware configuration used for the

tests.

Table 1: Hardware Configuration & Application details

Summary of content (6 pages)

PAGE 1
Comparing Sandy Bridge vs. Ivy Bridge processors for HPC applications Mayura Deshmukh - Dell, PSP team - NCSA, May 2014 As new server technologies become available, each generation is touted as being better, faster, more efficient, and laden with new features.
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16 core Sandy Bridge 20 core Ivy Bridge 24 core Ivy Bridge Processor 2 x Intel Xeon E5 2670 @ 2.6GHz (8-core) 2 x Intel Xeon E5 2697 v2 @ 2.7GHz (12-core) Memory Operating System File System 128GB 1600MHz 2 x Intel Xeon E5 2680 v2 @ 2.8GHz (10-core) 256GB 1866MHz* RHEL 6.4 Applications/ Benchmarks 256GB 1600MHz IBM GPFS, 700TB disk, 8 Storage Servers (PowerEdge R710) each 192GB RAM and 1.5TB of I/O cache ANSYS Fluent 14.5 LS-DYNA 6.1.1.790306 LAMMPS 12 MUMPS 4.10.0 (not used) MUMPS 4.10.
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Performance Gain with Ivy Bridge (12 core) over Sandy Bridge (8 core) 50% 46% 45% 40% 37% 35% 30% 26% 25% 25% 20% 16% 15% 12% 10% 5% 3% 0% HPL ANSYS Fluent LS-DYNA Simulia Abaqus 6.1.2- S4B Simulia Abaqus 6.12- E6 LAMMPS MUMPS 2 * 12 core IVB Figure 1 compares the performance of HPL. HPL solves a random dense linear system in doubleprecision arithmetic on distributed-memory systems. The problem size (N) used for the 12core IVB system was ~81% of the total memory size.
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comparing the rated base CPU frequency. In cases where Turbo is enabled, both IVB and SB processors can operate at higher clock rates and that should be taken into account when comparing results. Figure 2: Performance gain with Ivy Bridge (10-core) vs.
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Turbo mode was enabled for both the Abaqus benchmarks. The large arrays of equation solvers and datasets used in the simulation also require a large, fast memory system. For better performance with all applications, it is recommended to install enough memory so the job resides completely in physical memory to minimize I/O swapping to a local or network file system. The results show ~3% and 12% improvement with IVB 24c for the S4B and E6 benchmarks respectively.
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Conclusion NCSA’s testing results show that the Ivy Bridge processors provide better performance compared to the Sandy-Bridge for all the applications. The actual improvement depends on the application and its characteristics. The cost/benefit analysis of upgrading to IVB processors should be done based on a particular application workload, and not just based on number cores or higher clock rates.