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From: Mathieu Desnoyers via lttng-dev <lttng-dev@lists.lttng.org>
To: Valentin Grigorev <valentin.grigorev@jetbrains.com>
Cc: lttng-dev <lttng-dev@lists.lttng.org>
Subject: Re: LTTng user-space callstacks
Date: Thu, 26 Mar 2020 15:41:17 -0400 (EDT)	[thread overview]
Message-ID: <2022773652.13655.1585251677207.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <CABhb4uuE2QD8Asejaa+mjLPEVQAZrCxU6pwLp=QFqb2N3vD9nw@mail.gmail.com>


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----- On Mar 26, 2020, at 1:39 PM, lttng-dev <lttng-dev@lists.lttng.org> wrote: 

> Hello!

> Currently, callstack collection in LTTng is only available for kernel-space
> events with context fields callstack-kernel and callstack-user .

> Is it expected that callstack collection for LTTng-UST will be added too? And if
> it is expected, then how soon?

Hi Valentin, 

It is something that would be interesting and useful, but a lot of work would 
be needed to have stack-walking this is fast enough and reentrant wrt signal 
handlers. Unfortunately, the backtrace(3) functions do not meet those 
requirements. 

Also, for gathering user-space callstacks from the kernel tracer, it only works if 
all user-space is compiled with frame pointers. This is also a limitation that would 
require a lot of work to overcome neatly. 

None of those features are currently on any roadmap due to lack of customers 
showing interest in getting this done. 

Thanks, 

Mathieu 

-- 
Mathieu Desnoyers 
EfficiOS Inc. 
http://www.efficios.com 

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  reply	other threads:[~2020-03-26 19:41 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 17:39 LTTng user-space callstacks Valentin Grigorev via lttng-dev
2020-03-26 19:41 ` Mathieu Desnoyers via lttng-dev [this message]
2020-03-26 20:52   ` Milian Wolff via lttng-dev
2020-03-27 13:44     ` Valentin Grigorev via lttng-dev
2020-03-27 13:55       ` Mathieu Desnoyers via lttng-dev
2020-03-27 15:05         ` Valentin Grigorev via lttng-dev
2020-03-27 17:18         ` Milian Wolff via lttng-dev

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