You can start netperf with an interval of 10 milliseconds using: The tests here are performed with the -enable-spin flag set. Use of the -w and -b options requires building netperf with either the -enable-intervals or -enable-spin flag set. *Note: Alternatively, you can set less fine-grained intervals by compiling with the -enable-intervals flag. Of course, this precision comes at the cost of much higher CPU utilization as the CPU is spinning while waiting.
This approach allows you to set intervals with much finer granularity, by spinning in a tight loop until the next interval instead of waiting for a timer this keeps the cpu fully awake. Then, use the -w flag, which sets the interval time, and the -b flag, which sets the number of transactions sent per interval. You can start ping with an interval of 10 milliseconds using:įor netperf TCP_RR, we can enable some options for fine-grained intervals by compiling it with the -enable-spin flag. If you request an interval smaller than 1 millisecond, ping rounds down to 0 and sends requests as quickly as possible. For example, if you use an interval of 0.00299 seconds, this rounds down to 0.002 seconds, or 2 milliseconds. On Linux systems, this has a granularity of 1 millisecond, and rounds down. Ping uses an interval of 1 transaction per second while netperf issues the next transaction immediately when the previous transaction is complete.įortunately, both of these tools allow you to manually set the interval time between transactions, so you can see what happens when adjusting the interval time to match.įor ping, use the -i flag to set the interval, given in seconds or fractions of a second. To explain, this is largely an artifact of the different intervals the two tools used by default. The ping average latency reported is ~80 microseconds different than the netperf one ping reports a value more than twice that of netperf! Which test can we trust? Here, netperf reports an average latency of 66.59 microseconds. Microseconds Microseconds Microseconds Microseconds Tran/s MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.142.0.93 () port 0 AF_INET : histogram : spin interval : demo : first burst 0 $ netperf -H 10.142.0.93 -l 100 -t TCP_RR -v 2 -o min_latency,mean_latency,max_latency,stddev_latency,transaction_rate Once you set up PerfKit Benchmarker, you can run the simplest ping latency benchmark or a netperf TCP_RR latency benchmark using the following commands: This open-source tool allows you to run benchmarks on various cloud providers while automatically setting up and tearing down the virtual infrastructure required for those benchmarks. Example.Īs described in a previous blog post, when we run latency tests at Google in a cloud environment, our tool of choice is PerfKit Benchmarker (PKB). *Note: this uses global options: -H for remote-host and -t for test-name with a test-specific option -o for output-selectors. Here’s an example of using the test-specific -o flag so netperf outputs several latency statistics: With the -o flag, you can customize the output metrics to display the exact information you're interested in. In netperf, the TCP_RR and UDP_RR (RR=request-response) tests report round-trip latency.
#MEASURE NETWORD LATENCY IN NEOLOAD PLUS#
Network testing tools such as netperf can perform latency tests plus throughput tests and more. Ping does this using ICMP packets, and several tools based on ping such as nping, hping, and TCPing perform the same measurement using TCP packets.įor example, using the following command, ping sends one ICMP packet per second to the specified IP address until it has sent 100 packets. Which tools and whyĪll the tools in this area do roughly the same thing: measure the round trip time (RTT) of transactions. We'll also share our recommended commands for consistent, repeatable results running both intra-zone cluster latency and inter-region latency benchmarks. Google has lots of practical experience in latency benchmarking, and in this blog, we’ll share techniques jointly developed by Google and researchers at Southern Methodist University’s AT&T Center for Virtualization to inform your own latency benchmarking before and after migrating workloads to the cloud. And in most cases, we believe netperf returns the more representative answer to the question-you just need to pay attention to the details. A common question for cloud architects is “Just how quickly can we exchange a request and a response between two endpoints?” There are several tools for measuring round-trip network latency, namely ping, iperf, and netperf, but because they’re not all implemented and configured the same, different tools can return different results.
0 kommentar(er)
