Kprobes stress test prototype

[Masami Hiramatsu]

Hi,

Here is a script of kprobes stress test which uses
kprobes-ftrace engine. Currently, this doesn't use any
benchmarks for making a load.
Any updates, comments, and reports are welcome!

On KVM/x86-64, I've found some symbols must be marked
as __kprobes or blacklisted by using this script.

<always system hang up>
p irq_return
p start_critical_timing
p time_hardirqs_off
p bad_address
p trace_hardirqs_off_thunk
p restore

<not always, but potentially dangerous>
p start_critical_timings
p stop_critical_timing
p trace_hardirqs_on_thunk
p restore_norax

(I've encountered other odd memory corruptions too.
 However, I couldn't identify the reason, it might be a bug
 in kprobes or kvm.)

Basic usage is very simple.
Of course, this needs kprobes-ftrace engine patchset which
I posted to lkml (http://lkml.org/lkml/2009/6/1/461).

1. Make a working area and put the script;
 $ mkdir stest/
 $ cp kprobestest stest/

2. Run it.
 $ cd stest/
 $ ./kprobestest run

3. If kernel gets trouble, reboot it and run again.
 $ cd stest/
 $ ./kprobestest run

4. Repeat it, until all symbols are tested.

First, the test lists up all symbols in ".text" section, except
".text.kprobes"(*) and breaks it into sub-lists. Initially, each
sub-lists has 64 symbols and are stored into "gray" dir.
The test passes each sub-list to kprobes-ftrace engine and makes
a load(currently, just sleep 2secs).
If a sub-list hasn't made any trouble, it is moved to "white" dir.
If it causes a kernel panic etc., it is moved to "black" dir.

If "gray" dir becomes empty, it collects sub-lists in "black" dir
and breaks it into smaller sub-lists which has 16 symbols.

The test repeats it until each sub-list has just 1 symbol.

(*) You can also pass limited symbols which you are interested in
    instead of all symbols. In the step 2,
   $ cd stest/
   $ ./kprobestest run SYMBOL_LIST_FILE

  The SYMBOL_LIST_FILE must be written in the format of kprobes_events.
  This means you have to add a "p " prefix for each symbol. So,
  $ cat SYMBOL_LIST_FILE
  p symbol1
  p symbol2
  ...


Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

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