• Mathieu Desnoyers's avatar
    tracing, sched: LTTng instrumentation - scheduler · 0a16b607
    Mathieu Desnoyers authored
    Instrument the scheduler activity (sched_switch, migration, wakeups,
    wait for a task, signal delivery) and process/thread
    creation/destruction (fork, exit, kthread stop). Actually, kthread
    creation is not instrumented in this patch because it is architecture
    dependent. It allows to connect tracers such as ftrace which detects
    scheduling latencies, good/bad scheduler decisions. Tools like LTTng can
    export this scheduler information along with instrumentation of the rest
    of the kernel activity to perform post-mortem analysis on the scheduler
    About the performance impact of tracepoints (which is comparable to
    markers), even without immediate values optimizations, tests done by
    Hideo Aoki on ia64 show no regression. His test case was using hackbench
    on a kernel where scheduler instrumentation (about 5 events in code
    scheduler code) was added. See the "Tracepoints" patch header for
    performance result detail.
    Changelog :
    - Change instrumentation location and parameter to match ftrace
      instrumentation, previously done with kernel markers.
    [ mingo@elte.hu: conflict resolutions ]
    Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    Acked-by: default avatar'Peter Zijlstra' <peterz@infradead.org>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
fork.c 40.8 KB