Hi Philippe,

thanks for your response. The reason not to use LTTng is simple: while I 
develop on Linux, our client is chiefly using Windows with the mingw 
environment.

Best regards

Ansgar

________________________________
From: P
hilippe Proulx [eeppelitel...@gmail.com]
Sent: Friday, March 05, 2021 13:11
To: RADERMACHER Ansgar
Cc: lttng-dev@lists.lttng.org
Subject: Re: [lttng-dev] [barectf] How to ensure that last events before a 
crash get recorded

On Thu, Mar 4, 2021 at 10:28 RADERMACHER Ansgar via lttng-dev 
<lttng-dev@lists.lttng.org<mailto:lttng-dev@lists.lttng.org>> wrote:
Hi,

when doing tracing with barectf, the trace elements are written into a buffer 
first and only written when the buffer is full - or if the function 
barectf_platform_fs_fini gets called.
In case of a crash, it's therefore possible to loose some events. What is the 
best option to prevent this issue? I've used signal handlers that call the 
function barectf_platform_fs_fini. This seems to work well with Linux, but is 
not portable. When using the provided sample platform, there is also the option 
to reduce the buffer size, but this is not ideal, as trace events that are too 
big for the buffer are not written.

First question: why are you using barectf on Linux vs LTTng?

LTTng supports writing the sub-buffers to NVRAM and, if the system crashes, 
convert those sub-buffers to a CTF trace with the lttng-crash utility. See <
https://lttng.org/docs/v2.12/#doc-persistent-memory-file-systems>.

With NVRAM, you could do this with barectf with a corresponding platform using 
it. It's always up to the platform author to decide where buffers are and where 
complete packets go; it's not a feature of barectf as such.

Hope it helps,

Phil


Best regards

Ansgar


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