focal (8) softirqs-bpfcc.8.gz

NAME

       softirqs - Measure soft IRQ (soft interrupt) event time. Uses Linux eBPF/bcc.

SYNOPSIS

       softirqs [-h] [-T] [-N] [-d] [interval] [count]

DESCRIPTION

       This  summarizes  the  time spent servicing soft IRQs (soft interrupts), and can show this time as either
       totals or histogram distributions. A system-wide summary of this time is shown by  the  %soft  column  of
       mpstat(1), and soft IRQ event counts (but not times) are available in /proc/softirqs.

       This  tool  uses the irq:softirq_enter and irq:softirq_exit kernel tracepoints, which is a stable tracing
       mechanism. BPF programs can attach to tracepoints from Linux 4.7 only. An older version of this  tool  is
       available in tools/old, and uses kprobes instead of tracepoints.

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

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

       -h     Print usage message.

       -T     Include timestamps on output.

       -N     Output in nanoseconds

       -d     Show IRQ time distribution as histograms

EXAMPLES

       Sum soft IRQ event time until Ctrl-C:
              # softirqs

       Show soft IRQ event time as histograms:
              # softirqs -d

       Print 1 second summaries, 10 times:
              # softirqs 1 10

       1 second summaries, printed in nanoseconds, with timestamps:
              # softirqs -NT 1

FIELDS

       SOFTIRQ
              The kernel function name that performs the soft IRQ action.

       TOTAL_usecs
              Total time spent in this soft IRQ function in microseconds.

       TOTAL_nsecs
              Total time spent in this soft IRQ function in nanoseconds.

       usecs  Range of microseconds for this bucket.

       nsecs  Range of nanoseconds for this bucket.

       count  Number of soft IRQs in this time range.

       distribution
              ASCII representation of the distribution (the count column).

OVERHEAD

       This  traces  kernel  functions  and maintains in-kernel counts, which are asynchronously copied to user-
       space. While the rate of interrupts be very high (>1M/sec), this is a relatively efficient way  to  trace
       these  events,  and  so  the  overhead  is  expected  to  be small for normal workloads, but could become
       noticeable for heavy workloads. Measure in a test environment before use.

SOURCE

       This is from bcc.

              https://github.com/iovisor/bcc

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

OS

       Linux

STABILITY

       Unstable - in development.

AUTHORS

       Brendan Gregg, Sasha Goldshtein

SEE ALSO

       hardirqs(8)