From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers)
Subject: [lttng-dev] lttng enable-channel option for blocking
Date: Thu, 26 Apr 2012 17:16:27 -0400 [thread overview]
Message-ID: <20120426211627.GB1646@Krystal> (raw)
In-Reply-To: <4F992213.2090103@mentor.com>
* Woegerer, Paul (Paul_Woegerer at mentor.com) wrote:
> There are use-cases where loosing an event is not acceptable.
>
> Is there some way to make a userspace application block if the buffer is
> full (instead of discarding the event or overwriting an old event) ?
>
> I'm thinking about something like:
>
> lttng enable-channel myblockingchannel --block
>
> I know I can increase the subbuf-size but sometimes this is not an
> option (embedded targets with less RAM).
>
> A new channel option like --block would be a fine complement for the
> already existing options --discard and --overwrite.
>
> What do you think ?
I already thought about permitting this, but we currently don't. The
first thing I must say about this is that I prefer to wait a bit before
we add this feature, and think about its impact thoroughly, because
allowing the tracer to block applications gives a lot of power to the
tracer: e.g., if tracing is stopped due to error conditions, or disk
full, or network traffic slowdown, how do we handle the fact that this
might block progress in all traced applications ?
The current modes (discard and overwrite) let the applications continue
even if there is too much data being recorded into the trace buffers --
this is a "safe" approach.
How would you recommend dealing with the possible pitfalls of blocking
traced applications ? We would need a mechanism in place to ensure
gathering a trace cannot make applications unresponsive.
Thanks,
Mathieu
> Thanks,
> Paul
>
> --
> Paul Woegerer | SW Development Engineer
> Mentor Embedded(tm) | Prinz Eugen Stra?e 72/2/4, Vienna, 1040 Austria
> P 43.1.535991320
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>
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>
>
> _______________________________________________
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--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2012-04-26 21:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-26 10:23 Woegerer, Paul
2012-04-26 21:16 ` Mathieu Desnoyers [this message]
2012-04-27 7:28 ` Woegerer, Paul
2012-04-27 11:33 ` Mathieu Desnoyers
2012-04-27 11:50 ` Woegerer, Paul
2012-04-27 12:43 ` Mathieu Desnoyers
2012-04-27 16:15 ` Woegerer, Paul
2012-04-30 14:20 ` Mathieu Desnoyers
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