From: "Rafael J. Wysocki" <email@example.com>
To: Doug Smythies <firstname.lastname@example.org>
Cc: Peter Zijlstra <email@example.com>,
Daniel Lezcano <firstname.lastname@example.org>,
Giovanni Gherdovich <email@example.com>,
Linux PM <firstname.lastname@example.org>
Subject: Re: [PATCH v2] cpuidle: Use nanoseconds as the unit of time
Date: Sun, 10 Nov 2019 18:24:04 +0100
Message-ID: <6163696.37NBKbymtj@kreacher> (raw)
On Sunday, November 10, 2019 5:48:21 PM CET Rafael J. Wysocki wrote:
> On Fri, Nov 8, 2019 at 6:04 PM Doug Smythies <email@example.com> wrote:
> > On 2019.11.08 01:45 Rafael J. Wysocki wrote:
> > > On Fri, Nov 8, 2019 at 9:45 AM Doug Smythies <firstname.lastname@example.org> wrote:
> > >
> > ...
> > >> I have been running this v2 today, with both menu and teo
> > >> governors. Acquiring some baseline reference data to compare
> > >> to now. The menu governor response seems different (Supporting
> > >> information/graphs will come later).
> > >
> > > That may be good or bad, depending in what way it is different. :-)
> > My thinking was that the differences should be minimal between
> > the baseline (linux-next as of 2019.11.07) and plus your two patches.
> > Because this was a change of units, but not functionality.
> > Such is the case with the teo governor, but not the menu governor.
> > I have not tried the ladder or haltpoll governors, and don't intend to.
> > Now to attempt to isolate the issue in the code, which might take
> > considerable time.
> It looks like I have overlooked a unit conversion in menu or done a
> unit conversion twice somewhere.
I have found a bug, which should be addressed by the patch below.
If it still doesn't reduce the discrepancy, we'll need to look further.
| 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
@@ -516,8 +516,8 @@ static void menu_update(struct cpuidle_d
new_factor -= new_factor / DECAY;
if (data->next_timer_ns > 0 && measured_ns < MAX_INTERESTING)
- new_factor += RESOLUTION * div64_u64(measured_ns,
+ new_factor += div64_u64(RESOLUTION * measured_ns,
* we were idle so long that we count it as a perfect
next prev parent reply index
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 10:30 [PATCH] " Rafael J. Wysocki
2019-11-07 14:25 ` [PATCH v2] " Rafael J. Wysocki
2019-11-08 1:44 ` Rafael J. Wysocki
2019-11-08 8:45 ` Doug Smythies
2019-11-08 9:45 ` Rafael J. Wysocki
2019-11-08 17:04 ` Doug Smythies
2019-11-10 16:48 ` Rafael J. Wysocki
2019-11-10 17:24 ` Rafael J. Wysocki [this message]
2019-11-10 18:09 ` Doug Smythies
2019-11-10 22:12 ` Doug Smythies
2019-11-11 21:29 ` Rafael J. Wysocki
2019-11-08 9:39 ` Peter Zijlstra
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