linux-kernel - Re: [PATCH v7 09/16] tracing: Add hist trigger snapshot() action test case

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Message-Id: <20181128111558.5869fa4be7104314e833a801@kernel.org>
Date:   Wed, 28 Nov 2018 11:15:58 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Tom Zanussi <zanussi@...nel.org>
Cc:     rostedt@...dmis.org, tglx@...utronix.de, namhyung@...nel.org,
        vedang.patel@...el.com, bigeasy@...utronix.de,
        joel@...lfernandes.org, mathieu.desnoyers@...icios.com,
        julia@...com, linux-kernel@...r.kernel.org,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH v7 09/16] tracing: Add hist trigger snapshot() action
 test case

Hi Tom,

On Tue, 27 Nov 2018 16:53:45 -0600
Tom Zanussi <zanussi@...nel.org> wrote:

> > > +ping $LOCALHOST -c 3
> > > +nice -n 1 ping $LOCALHOST -c 3
> > > +
> > > +echo 0 > /sys/kernel/debug/tracing/events/sched/enable
> > 
> > Shouldn't we stop tracing instead of disabling the event?
> > 
> 
> This is just reversing the enable, so should be fine, but I can stop
> tracing instead if you prefer.

Oops, maybe we have to check the difference between event enabling and
trace enabling.
echo 0 > tracing_on will stop writing ring buffer, but event may continue
to be called. Does this mean hist will be updated? (and I guess preferrable
behavior is to stop hist too, isn't it?)

Thank you,


-- 
Masami Hiramatsu <mhiramat@...nel.org>