Re: [RFC PATCH] LTTng instrumentation mm (updated)

[fche@redhat.com (Frank Ch. Eigler)]

Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> writes:

> [...]
>> > We would like to be able to tell which swap file the information has
>> > been written to/read from at any given time during the trace.
>> 
>> Oh, tracing is expected to be on at all times?  I figured someone would
>> encounter a problem, then turn it on to dig down a little deeper, then
>> turn it off.
>
> Yep, it can be expected to be on at all times, especially on production
> systems using "flight recorder" tracing to record information in a
> circular buffer [...]

Considering how early in the boot sequence swap partitions are
activated, it seems optimistic to assume that the monitoring equipment
will always start up in time to catch the initial swapons.  It would
be more useful if a marker parameter was included in the swap events
to let a tool/user map to /proc/swaps or a file name.

- FChE

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