This is the mail archive of the systemtap@sources.redhat.com mailing list for the systemtap project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

runtime libraries application on schedule()


Hi Martin,

I noticed that you checked in a bunch of runtime stuff today. I was thinking about possible applications/instrumentations using the runtime library. One of the things I was thinking was instrumentin the schedule() function. It is called each time the processor yields. I assume that many of the device drivers are written to yield the processor when they are waiting for IO with a schedule.

Use a jprobe to instrument the entry to schedule().
Record the pid and the return address.

The information could be analyzed in a sevral different ways:

1) sum based on return address to find out which schedule points are getting hit all the time
2) sum the counts by pid to figure out which pids are getting rescheduled a lot
3) find out pid hitting which schedule() points
4) find out schedule() point being encountered by which process


Comments on implementing this instrumentation?

-Will


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]