LTTng 0.52, scheduler instrumentation

From: Mathieu Desnoyers
Date: Thu Nov 06 2008 - 20:08:38 EST


Hi,

I just released LTTng 0.52 for 2.6.27.4. It fixes the stuff I dreamt
about this morning. ;-)

Ingo what do you think about this first point ?

- I now only use 2 bytes to encode the task->state field in the trace.
However it seems that 1 byte would be enough (bitmask of values 0 to
127), except that -1 is used for "unrunnable". But when it's
unrunnable, it should "never" be reach scheduler events, right ?

Changelog :
- Add kernel command line : force_tsc_sync=1 to force tsc
synchronization at boot.
- Supports AMD64 X2 box with unsynchronized TSCs very well. Includes
a warning that tells users to try
force_tsc_sync=1 idle=poll and to disable PowerNow or Speedstep to get
synchronized timestamp counters on x86. This workaround works very
well.
- Default to no LTT alignment for traces if
HAVE_EFFICIENT_UNALIGNED_ACCESS is selected.
- Fixed mixed up irq entry field names in (appeared in 0.51).

Some testing would be required with virtualization to see how it
behaves.

Mathieu

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Mathieu Desnoyers
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