linux-kernel - Re: [RFC PATCH 0/5] BLOG: per-task logging contexts with Ceph consumer

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Message-ID: <CAO8a2SgZ8gZ0VdtBAeW8wLMDxa+Eq42ppr-99tUpiu3Tpwqz5w@mail.gmail.com>
Date: Sat, 25 Oct 2025 20:54:00 +0300
From: Alex Markuze <amarkuze@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, Liam.Howlett@...cle.com, akpm@...ux-foundation.org, 
	bsegall@...gle.com, david@...hat.com, dietmar.eggemann@....com, 
	idryomov@...il.com, mingo@...hat.com, juri.lelli@...hat.com, kees@...nel.org, 
	lorenzo.stoakes@...cle.com, mgorman@...e.de, mhocko@...e.com, rppt@...nel.org, 
	peterz@...radead.org, surenb@...gle.com, vschneid@...hat.com, 
	vincent.guittot@...aro.org, vbabka@...e.cz, xiubli@...hat.com, 
	Slava.Dubeyko@....com
Subject: Re: [RFC PATCH 0/5] BLOG: per-task logging contexts with Ceph consumer

Please correct me if I am wrong, I was not aware that ftrace is used
by any kernel component as the default unstructured logger.
This is the point of BLog, having a low impact unstructured logger,
it's not always possible or easy to provide a debug kernel where
ftarce is both enabled and used for dumping logs.
Having an always-on binary logger facilitates better debuggability.
When anything happens, a client with BLog has the option to send a
large log file with their report.
An additional benefit is that each logging buffer is attached to the
associated tasks and the whole module has its own separate cyclical
log buffer.

On Sat, Oct 25, 2025 at 5:59 PM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> On Sat, 25 Oct 2025 13:50:39 +0300
> Alex Markuze <amarkuze@...hat.com> wrote:
>
> > First of all, Ftrace is for debugging and development; you won't see
> > components or kernel modules run in production with ftrace enabled.
> > The main motivation is to have verbose logging that is usable for
> > production systems.
>
> That is totally untrue. Several production environments use ftrace. We
> have it enabled and used in Chromebooks and in Android. Google servers
> also have it enabled.
>
>
> > The second improvement is that the logs have a struct task hook which
> > facilitates better logging association between the kernel log and the
> > user process.
> > It's especially handy when debugging FS systems.
>
> So this is for use with debugging too?
>
> >
> > Specifically we had several bugs reported from the field that we could
> > not make progress on without additional logs.
>
> This still doesn't answer my question about not using ftrace. Heck,
> when I worked for Red Hat, we used ftrace to debug production
> environments. Did that change?
>
> -- Steve
>