linux-kernel - Re: [PATCH 1/2] tracing: show size of requested buffer

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Message-ID: <robbat2-20211009T000917-463381491Z@orbis-terrarum.net>
Date:   Sat, 9 Oct 2021 00:21:29 +0000
From:   "Robin H. Johnson" <robbat2@...too.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     "Robin H. Johnson" <robbat2@...too.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        rjohnson@...italocean.com,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH 1/2] tracing: show size of requested buffer

On Fri, Oct 08, 2021 at 06:13:48PM -0400, Steven Rostedt wrote:
> On Thu, 7 Oct 2021 17:26:04 +0000
> "Robin H. Johnson" <robbat2@...too.org> wrote:
> 
> > I was trying to think further what would make sense for the constant.
> > - What are the negative impacts of a too-large value?
> > - Is there demand for more reconfigurability? 
> > - Should PERF_MAX_TRACE_SIZE be a knob in Kconfig?
> 
> One thing you haven't discussed was, have you hit this warning, and if so,
> what were you doing?
Ah, I covered that in patch 2/2 in the original series, which discussed
why I was raising the limit, and how I came to the 8K value for
PERF_MAX_TRACE_SIZE.
https://lore.kernel.org/all/20210831043723.13481-2-robbat2@gentoo.org/

To summarize here:
$work requires that all employees run endpoint security software from
SentinalOne [1]. I can see that it uses trace/perf stuff to dig deeply
into what's taking place on the system.

Something in my personal setup/configuration, leads to SentinelOne
getting large perf backlogs during heavy workloads, primarily when I'm
doing deep things with containers (esp with tun devices inside
containers). I haven't been able to narrow it down much more than that,
and I don't have the source to SentinelOne at all.

It does feel like SentinelOne either has a leak of some sort, or gets a
backlog of work that takes a noticible amount of time to clean up.

[1] https://www.sentinelone.com/

-- 
Robin Hugh Johnson
Gentoo Linux: Dev, Infra Lead, Foundation Treasurer
E-Mail   : robbat2@...too.org
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