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