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From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Doug Smythies <dsmythies@telus.net>,
	"'Rafael J. Wysocki'" <rafael@kernel.org>,
	'Ingo Molnar' <mingo@redhat.com>,
	'Peter Zijlstra' <peterz@infradead.org>,
	'Linux PM' <linux-pm@vger.kernel.org>,
	'Vincent Guittot' <vincent.guittot@linaro.org>,
	'Joel Fernandes' <joel@joelfernandes.org>,
	"'v4 . 18+'" <stable@vger.kernel.org>,
	'Linux Kernel Mailing List' <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cpufreq: schedutil: Don't skip freq update when limits change
Date: Tue, 6 Aug 2019 09:30:59 +0530	[thread overview]
Message-ID: <20190806040059.ty4qhjarx4obomhs@vireshk-i7> (raw)
In-Reply-To: <1599417.3YyTWY6lWL@kreacher>

On 02-08-19, 11:11, Rafael J. Wysocki wrote:
> On Friday, August 2, 2019 5:48:19 AM CEST Viresh Kumar wrote:
> > On 01-08-19, 10:57, Doug Smythies wrote:
> > > Disagree.
> > > All I did was use a flag where it used to be set to UNIT_MAX, to basically
> > > implement the same thing.
> > 
> > And the earlier code wasn't fully correct as well, that's why we tried
> > to fix it earlier.
> 
> Your argument seems to be "There was an earlier problem related to this, which
> was fixed, so it is fragile and I'd rather avoid it".  Still, you are claiming that the
> code was in fact incorrect and you are not giving convincing arguments to
> support that.
> 
> > So introducing the UINT_MAX thing again would be
> > wrong, even if it fixes the problem for you.
> 
> Would it be wrong, because it would reintroduce the fragile code, or would it
> be wrong, because it would re-introduce a bug?  What bug if so?

There will be two issues here if that patch is reintroduced:

- It will cause the BUG to reappear, which was fixed by the earlier
  commit. The commit log of ecd28842912 explains the bug in detail.

- And overriding next_freq as a flag will make the code fragile and we
  may have similar bugs coming up.

But yeah, lets continue discussion on the intel-pstate patch now.

-- 
viresh

  parent reply	other threads:[~2019-08-06  4:01 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-18  6:26 [PATCH] Revert "cpufreq: schedutil: Don't set next_freq to UINT_MAX" Doug Smythies
2019-07-18 10:28 ` Viresh Kumar
2019-07-18 15:46   ` Doug Smythies
2019-07-22  6:49     ` Viresh Kumar
2019-07-22  6:51 ` [PATCH] cpufreq: schedutil: Don't skip freq update when limits change Viresh Kumar
2019-07-23  7:10   ` Doug Smythies
2019-07-23  9:13     ` Rafael J. Wysocki
2019-07-23  9:15     ` Viresh Kumar
2019-07-23 10:27       ` Rafael J. Wysocki
2019-07-24 11:43         ` Viresh Kumar
2019-07-25 15:20           ` Doug Smythies
2019-07-26  3:26             ` Viresh Kumar
2019-07-26  6:57             ` Viresh Kumar
2019-07-29  7:55               ` Doug Smythies
2019-07-29  8:32                 ` Viresh Kumar
2019-07-29  8:37                   ` Rafael J. Wysocki
2019-08-01  0:20                     ` Doug Smythies
2019-08-01  6:17                       ` Viresh Kumar
2019-08-01  7:47                         ` Rafael J. Wysocki
2019-08-01  7:55                           ` Viresh Kumar
2019-08-01 17:57                         ` Doug Smythies
2019-08-02  3:48                           ` Viresh Kumar
2019-08-02  9:11                             ` Rafael J. Wysocki
2019-08-02  9:19                               ` Rafael J. Wysocki
2019-08-06  4:00                               ` Viresh Kumar [this message]
2019-07-31  2:58 Viresh Kumar
2019-07-31 23:19 ` Doug Smythies

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