NAME¶

syscount.bt - Count system calls. Uses bpftrace/eBPF.

SYNOPSIS¶

syscount.bt

DESCRIPTION¶

This counts system calls (syscalls), printing a summary of the top ten syscall IDs, and the top ten process names making syscalls. This can be helpful for characterizing the kernel and resource workload, and finding applications who are using syscalls inefficiently.

This works by using the tracepoint:raw_syscalls:sys_enter tracepoint.

Since this uses BPF, only the root user can use this tool.

REQUIREMENTS¶

CONFIG_BPF and bpftrace.

EXAMPLES¶

Count system calls until Ctrl-C is hit:

# syscount.bt

OUTPUT¶

Top 10 syscalls IDs:

This shows the syscall ID number (in @syscall[]) followed by a count for this syscall during tracing. To see the syscall name for that ID, you can use "ausyscall --dump", or the bcc version of this tool that does translations.

Top 10 processes:

This shows the process name (in @process[]) followed by a count of syscalls during tracing.

OVERHEAD¶

For most applications, the overhead should be manageable if they perform 1000's or even 10,000's of syscalls per second. For higher rates, the overhead may become considerable. For example, tracing a microbenchmark loop of 4 million calls to geteuid(), slows it down by 2.4x. However, this represents tracing a workload that has a syscall rate of over 4 million syscalls per second per CPU, which should not be typical (in one large cloud production environment, rates of between 10k and 50k are typical, where the application overhead is expected to be closer to 1%).

For comparison, strace(1) in its current ptrace-based implementation (which it has had for decades) runs the same geteuid() workload 102x slower (that's one hundred and two times slower).

SOURCE¶

This is from bpftrace.

https://github.com/iovisor/bpftrace

Also look in the bpftrace distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.

This is a bpftrace version of the bcc tool of the same name. The bcc version provides different command line options, and translates the syscall IDs to their syscall names.

https://github.com/iovisor/bcc

OS¶

Linux

STABILITY¶

Unstable - in development.

AUTHOR¶

Brendan Gregg

SEE ALSO¶

strace(1)