Intel AT80615005760AB, BX80615E74830 User Manual

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Figure 1 - 2012 Processor Numbering Example

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Intel® Xeon® Processor E7 Family

Performance Brief: Model Number Characteristics and Impact to Performance

Intel® Xeon® Processor E7 Family

Performance and Model Numbers

Intel® Xeon® Processor E7-8800/4800/2800 Product Families Characteristics and Impact to Performance

EXECUTIVE SUMMARY

Just like many automobile manufacturers and other companies that have multiple product lines within their product family, server processors have model numbers to help distinguish the differences in features and delineate value. As your business grows, so does demand for your products and / or services with additional customers, users, and transactions that strain your current IT infrastructure and back-end databases. The Intel® Xeon® brand helps customers

select the appropriate product line and family stack as their demand justifies it1.

This paper focuses specifically on the Intel Xeon processor E7 family which is designed to be expandable and scalable for larger deployments of businessor mission-critical workloads such as on-line transaction processing, physical-to-virtual machine consolidation projects, business intelligence, customer relationship management (CRM), and enterprise resource planning (ERP) / line-of-business applications that generate revenue. The model numbers (see Figure 1) help differentiate the capabilities of the processors and in the case of the Intel Xeon processor E7 product family, the wayness or maximum number of processors (CPUs or sockets) in a node can be two, four, or eight (contrasted to the Intel Xeon processor E3 or E5 families, which support only one or two/four processors, respectively). Performance may scale as the number of processors installed (wayness) in a server is increased (up to 94% efficiency as published in this paper); but in a two-way server, regardless of the actual processor wayness capability, the throughput application performance would be expected to be the same.

MODEL NUMBERS AND SCALABILITY

For the Intel Xeon processor E7 family, processor models (also called SKUs) are available in three wayness configurations – two, four, or eight socket native support (no third party node controller required to connect the

sockets together). Within a given Intel Xeon processor E7-xxxx SKU, the difference in wayness is irrelevant if populated in only a two-socket node and corresponding performance differences are negligible. For example, the top-bin Intel Xeon processor E7-8870/E7-4870/E7-2870 all have the same socket type (8) and the same

Figure 3 - Intel Xeon processor E7 family scalability to support 2- to 256-sockets3

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processor SKU (70); which indicates same core frequency of 2.4 GHz, the same Intel® QuickPath Interconnect speed of 6.4 GT/s, the same last-level cache (LLC) of 30 MB, and the same number of cores at 10 per processor.

So the only difference is in the first product family number represents wayness (2, 4, or 8) capability indicating that the Intel Xeon processor E7-4xxx and E7-8xxx models can scale natively beyond just 2-sockets (see Figure 2 below). It is common IT practice to buy “headroom” by purchasing a larger server but only initially partitioning a portion of the processor sockets for today’s level of requirements allowing for future compute power expansion as the number of users, transactions, or problem fidelity increases. Ideally, with perfect scaling, you can double the number of users, for example, when doubling the number of processor compute power (assuming storage, memory, and I/O are scaled as to not be the bottleneck). However, when any of these otherwise identical processors are populated in 2-sockets only though, performance throughput should be expected to be the same.

Figure 2 - Intel® Xeon® Processor E7-8800/4800/2800 Product Family Numbering2

PERFORMANCE IMPACT

For the purposes of demonstrating the impact of model numbers on performance, the top of the advanced capability levels of each product family is compared below (Intel Xeon processor E7-8870/4870/2870). Figure 3 below illustrates the options original equipment manufacturers (OEMs) have in designing an Intel Xeon processor E7 family-based server.

Looking at the first number in the Intel Xeon processor E7 family, -8xxx, -4xxx or -2xxx, which represents the number of processors natively supported in a server, the processors can scale to support the increased number of users, transactions or throughput as additional sockets are tested in performance benchmarks. The typical example of this can be found while using the SPECint*_rate_base2006

benchmark that is fairly representative of typical integer-based, compute-intensive server applications to test the

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number of users (typically matches the number of logical threads seen by the Operating System, OS) simultaneously running a problem on a given server. The performance scaling is calculated by dividing the resulting score from the maximum number of processors populated in one server by the score of the server with n-way processors populated in another server configuration. So from 2- to 4- to 8-socket-based servers, the perfect scaling would be four times, meaning that the number of users supported (or problems solved) in the 8- socket server is four times more than what a 2-socket server could support. The efficiency is measured by how close a scale-up server performs comparatively to that perfect scaling, which in this case is quite reasonable at up to 94% efficiency (see Figure 4 below).

2-socket 4-socket 8-socket

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Figure 4 - Scaling of supported users on multi-processor servers4

The Intel Xeon processor E7-8870 can be populated in a 2-, 4-, or 8-socket server configuration. This is due to the Intel® QuickPath Interconnect (Intel® QPI) that allows the processors to share resources by allowing all of the components to access other components through the mainboard network. Similar to the Intel Xeon processor E78870, the E7-4870 model supports 2- or 4-socket server configurations; but on the Intel Xeon processor E7-2870, only 2-sockets can be populated in a server node (though multiple nodes can be joined together to form a larger single server image ≥2S – see Figure 3 above).

There are no characteristics in each of the three processors noted above that differ, other than the wayness capability. All three processors operate in the same number of available cores per socket, core frequency, Intel® QPI speed, and cache structure (see Figure 2 above). Therefore, in a 2-socket server configuration, the performance delta between the three will only be typical run-to-run variation due to a number of factors including manufacturing variances that may affect the length of time the processors run above their marked frequency using Intel® TurboBoost Technology. SPEC* allows for up to 1.75% variation. This hypothesis was confirmed through testing using Intel internal labs and as seen in Figure 5 below as there is less than 0.5% difference in performance between the three processors when in the same two-socket server configuration (see Table 1 below for complete list of equivalent processor SKUs).

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