cpipe --- counting pipe

Introduction

Did you ever want to know how fast your tar is or how much data it has transferred already. How about using socket or nc to copy files either with or without compression over a fast network connection, which one is faster?

If you want to know the answer, use cpipe as a totally unscientific approach to measure throughput. Cpipe copies its standard input to its standard output while measuring the time it takes to read an input buffer and write an output buffer. Statistics of average throughput and the total amount of bytes copied are printed to the standard error output.

Example

The command

  tar cCf / - usr | cpipe -vr -vw -vt > /dev/null

results in an output like

...
  in:  19.541ms at    6.4MB/s (   4.7MB/s avg)    2.0MB
 out:   0.004ms at   30.5GB/s (  27.1GB/s avg)    2.0MB
thru:  19.865ms at    6.3MB/s (   4.6MB/s avg)    2.0MB
...

The first column shows the times it takes to handle one buffer of data (128kB by default). The read-call took 19.541ms, the write-call to /dev/null took just 0.004ms and from the start of the read to the end of write, it took 19.865ms.

The second column shows the result of dividing the buffer size (128kB by default) by the times in the first column.