From: Matthias Kaehlcke <mka@chromium.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Kevin Hilman <khilman@kernel.org>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@redhat.com>,
Douglas Anderson <dianders@chromium.org>,
Linux PM <linux-pm@vger.kernel.org>,
Amit Kucheria <amit.kucheria@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] PM / Domains: Add tracepoints
Date: Wed, 16 Oct 2019 11:13:17 -0700 [thread overview]
Message-ID: <20191016181317.GP87296@google.com> (raw)
In-Reply-To: <CAPDyKFpE0LoxXAR=2JvPi8pvb-6_q4rgs-A4D6OU7XuP1XEtbg@mail.gmail.com>
On Wed, Oct 16, 2019 at 03:47:44PM +0200, Ulf Hansson wrote:
> On Tue, 15 Oct 2019 at 19:19, Matthias Kaehlcke <mka@chromium.org> wrote:
> >
> > Hi Ulf,
> >
> > On Tue, Oct 15, 2019 at 02:37:42PM +0200, Ulf Hansson wrote:
> > > On Tue, 1 Oct 2019 at 18:35, Matthias Kaehlcke <mka@chromium.org> wrote:
> > > >
> > > > On Fri, Sep 27, 2019 at 04:42:39AM -0400, Steven Rostedt wrote:
> > > > > On Thu, 26 Sep 2019 15:04:38 -0700
> > > > > Matthias Kaehlcke <mka@chromium.org> wrote:
> > > > >
> > > > > > Define genpd_power_on/off and genpd_set_performance_state
> > > > > > tracepoints and use them.
> > > > >
> > > > > I agree with Greg about adding a "why" you need this. But, in case
> > > > > there's a good reason to have this, I have comments about the code
> > > > > below.
> > > >
> > > > Thanks Greg and Steven for your comments.
> > > >
> > > > How about this instead:
> > > >
> > > > Add tracepoints for genpd_power_on, genpd_power_off and
> > > > genpd_set_performance_state. The tracepoints can help with
> > > > understanding power domain behavior of a given device, which
> > > > may be particularly interesting for battery powered devices
> > > > and suspend/resume.
> > >
> > > Apologize for the delay, no excuse!
> > >
> > > I don't mind adding trace events, as long as it's for good reasons -
> > > and to me, that seems a bit questionable here.
> > >
> > > According to the above, I believe the information you need is already
> > > available via genpd's debugfs interface, no?
> >
> > Not in all cases, e.g. you can't peek at sysfs while the device is
> > suspended.
>
> Not sure I get this right. If a device that is attached to a genpd
> that is runtime suspended, for sure you can have a look at the genpd
> debugfs to see its current status.
Sorry, I used an ambiguous terminology by talking about 'the device',
I was referring to system suspend.
> > Also sysfs doesn't help much with seeing that a PD is
> > toggling between on an off for some (possibly legitimate) reason.
>
> Well, you could look at the "active_time" and the "total_idle_time"
> nodes for the genpd in question. Those should change accordingly.
Ok, thanks for the pointer!
prev parent reply other threads:[~2019-10-16 18:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 22:04 [PATCH v1] PM / Domains: Add tracepoints Matthias Kaehlcke
2019-09-27 5:36 ` Greg Kroah-Hartman
2019-09-27 8:42 ` Steven Rostedt
2019-10-01 16:35 ` Matthias Kaehlcke
2019-10-01 17:03 ` Steven Rostedt
2019-10-01 17:42 ` Matthias Kaehlcke
2019-10-01 18:08 ` Steven Rostedt
2019-10-01 19:37 ` Matthias Kaehlcke
2019-10-02 7:55 ` Rafael J. Wysocki
2019-10-02 19:10 ` Pavel Machek
2019-10-15 12:37 ` Ulf Hansson
2019-10-15 17:19 ` Matthias Kaehlcke
2019-10-16 13:47 ` Ulf Hansson
2019-10-16 18:13 ` Matthias Kaehlcke [this message]
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