2.4.1. RT-linux Performance Guide¶

2.4.1.1.1. LMBench¶

LMBench is a collection of microbenchmarks of which the memory bandwidth and latency related ones are typically used to estimate processor memory system performance.

Latency: lat_mem_rd-stride128-szN, where N is equal to or smaller than the cache size at given level measures the cache miss penalty. N that is at least double the size of last level cache is the latency to external memory.

Bandwidth: bw_mem_bcopy-N, where N is is equal to or smaller than the cache size at a given level measures the achivable memory bandwidth from software doing a memcpy() type operation. Typical use is for external memory bandwidth calculation. The bandwidth is calculated as byte read and written counts as 1 which should be roughly half of STREAM copy result.

Table: LM Bench Metrics

2.4.1.1.2. Dhrystone¶

Dhrystone is a core only benchmark that runs from warm L1 caches in all modern processors. It scales linearly with clock speed. For standard ARM cores the DMIPS/MHz score will be identical with the same compiler and flags.

Table: Dhrystone Benchmark

2.4.1.1.3. Whetstone¶

Table: Whetstone Benchmark

2.4.1.1.4. Linpack¶

Linpack measures peak double precision (64 bit) floating point performance in sloving a dense linear system.

Table: Linpack Benchmark

2.4.1.1.5. NBench¶

Table: NBench Benchmarks

2.4.1.1.6. Stream¶

STREAM is a microbenchmarks for measuring data memory system performance without any data reuse. It is designed to miss on caches and exercise data prefetcher and apeculative accesseses. it uses double precision floating point (64bit) but in most modern processors the memory access will be the bottleck. The four individual scores are copy, scale as in multiply by constant, add two numbers, and triad for multiply accumulate. For bandwidth a byte read counts as one and a byte written counts as one resulting in a score that is double the bandwidth LMBench will show.

Table: Stream

2.4.1.1.7. CoreMarkPro¶

CoreMark®-Pro is a comprehensive, advanced processor benchmark that works with and enhances the market-proven industry-standard EEMBC CoreMark® benchmark. While CoreMark stresses the CPU pipeline, CoreMark-Pro tests the entire processor, adding comprehensive support for multicore technology, a combination of integer and floating-point workloads, and data sets for utilizing larger memory subsystems.

Table: CoreMarkPro

Table: CoreMarkPro for Two Cores

2.4.1.1.8. MultiBench¶

MultiBench™ is a suite of benchmarks that allows processor and system designers to analyze, test, and improve multicore processors. It uses three forms of concurrency: Data decomposition: multiple threads cooperating on achieving a unified goal and demonstrating a processor’s support for fine grain parallelism. Processing multiple data streams: uses common code running over multiple threads and demonstrating how well a processor scales over scalable data inputs. Multiple workload processing: shows the scalability of general-purpose processing, demonstrating concurrency over both code and data. MultiBench combines a wide variety of application-specific workloads with the EEMBC Multi-Instance-Test Harness (MITH), compatible and portable with most any multicore processors and operating systems. MITH uses a thread-based API (POSIX-compliant) to establish a common programming model that communicates with the benchmark through an abstraction layer and provides a flexible interface to allow a wide variety of thread-enabled workloads to be tested.

Table: Multibench

2.4.1.2.1. Shield (dedicated core) Case¶

shield_shell()
{
create_cgroup nonrt 0
create_cgroup rt 1
for pid in $(cat /sys/fs/cgroup/tasks); do /bin/echo $pid > /sys/fs/cgroup/nonrt/tasks; done
/bin/echo $$ > /sys/fs/cgroup/rt/tasks
}

Table: Cyclic test for Two Cores

2.4.1.3.1. CPSW Ethernet Driver¶

TCP Bidirectional Throughput

Table: CPSW TCP Bidirectional Throughput

UDP Throughput (0% loss)

Table: CPSW UDP Egress Throughput

Table: CPSW UDP Ingress Throughput

Table: CPSW UDP Ingress Throughput (possible loss)

2.4.1.4.1. PCIe-NVMe-SSD¶

• Filesize used is: 10G
• FIO command options: –ioengine=libaio –iodepth=4 –numjobs=1 –direct=1 –runtime=60 –time_based
• Platform: Speed 8GT/s, Width x1
• SSD being used: Lite-On Technology Corporation M8Pe Series NVMe SSD [14a4:22f1] (rev 01)

2.4.1.6.1. USB Host Controller¶

Setup : SAMSUNG 850 PRO 2.5” 128GB SATA III Internal Solid State Drive (SSD) used with Inateck ASM1153E enclosure is connected to usb port under test. File read/write performance data is captured.