Administrator Guide

Test Scope and Configurations

To characterize performance variances, two testing devices were

configured (see Figure 3). The SNAP I/O configuration used the

PowerEdge R740 while the unbalanced one-NIC configuration and

balanced two-NIC configuration used the PowerEdge R740xd. Aside

from the chassis form factor and SNAP I/O riser, both pieces of

apparatus were configured identically so the comparison was apples-

to-apples.

Two test platforms were used to measure network bandwidth, latency,

UPI utilization and CPU utilization. The first set of tests measured

performance for an OS test scope, including benchmarks like iperf,

qperf, Pcm.x and top. The second set of tests measured performance

for a Docker test scope, including benchmarks like iperf3 and qperf.

Performance Comparisons

Latency

Figure 4 used the OS-level qperf test tool to compare

the latency of the SNAP I/O solution against two

benchmarks; the first being the NIC connected to the

PCIe bus local to the CPU, and the second being the

remote CPU that must cross the UPI to connect to the

NIC. The graph shows that for both 100GbE and

25GbE NICs, the SNAP I/O latency is reduced by

more than 40% compared to the latency experienced

by the remote CPU accessing the single NIC.

Figure 5 compares the latency of the SNAP I/O

solution against the same two configurations in the

docker environment. Like Figure 3, the graphs show

that the latency of the SNAP I/O solution has reduced

by more than 40% compared to the latency

experienced by the remote CPU.

Bandwidth

Figure 6 to the right compares the bandwidth of the

SNAP I/O against the same two configurations by

applying 5 stream memory tests to ensure there is

enough UPI traffic for accurate iperf bandwidth

testing. The graphs show that for 100G NICs, the

bandwidth of the SNAP I/O solution compared to the

bandwidth of the remote CPU has improved by 24%

for OS testing and by 9.2% for docker testing.

Figure 3: Table displaying the two pieces

of apparatus used for testing

Figure 4: OS latency (in µs) of various configurations; local CPU,

remote CPU and SNAP I/O

Figure 5: Docker latency (in µs) of various configurations; local

CPU, remote CPU and SNAP I/O

Figure 6: OS/Docker bandwidth (in µs) of various

configurations; local CPU, remote CPU and SNAP I/O