Re: "lttng enable-channel --tracefile-size" bug

From: John Smith <whalajam@gmail.com>
To: Julien Desfossez <jdesfossez@efficios.com>
Cc: lttng-dev@lists.lttng.org
Subject: Re: "lttng enable-channel --tracefile-size" bug
Date: Sat, 28 May 2016 14:59:13 -0700	[thread overview]
Message-ID: <CANgVouUbJtNjBDajia1E3+CCEg95-=tnqfzBW7ukQxQbn9N_6Q__12466.4285257042$1464631045$gmane$org@mail.gmail.com> (raw)
In-Reply-To: <57499B75.80203@efficios.com>

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Julien,
thanks, I was mislead by the 2.7 documentation saying:
"...parameters of enable-channel are --tracefile-sizeand --tracefile-count,
which respectively limit the size of each trace file and the their count
for a given channel. "
In this case the tracefile-size option should be removed, will it become
useful in the future releases or has a more subtle use?

thanks, John

On Sat, May 28, 2016 at 6:21 AM, Julien Desfossez <jdesfossez@efficios.com>
wrote:

> > Hi,
> > it looks like for the "enable-channel" command, "tracefile-size" option
> > doesn't take effect, bellow are all the options, the resulted files have
> > the actual size the same as the size specified by subbuf-size option:
> >
> > # lttng -V
> > lttng (LTTng Trace Control) 2.7.1 - Herbe à Détourne
> >
> > $ lttng enable-channel chan_name -u -s session_name --discard
> > --num-subbuf 8
> >             --subbuf-size 32M --tracefile-size 8K --tracefile-count 8
> > --buffers-pid
>
> Yes, that is the expected behaviour, we work with packets (sub-buffers),
> so the smallest unit we can store is the subbuf-size.
>
> With 2.7.3 I get this warning when I try your command:
> Warning: Tracefile size rounded up from (8192) to subbuffer size (33554432)
>
> Julien
>

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