From: Thomas Gleixner <tglx@linutronix.de> To: Eduardo Valentin <edubezval@gmail.com> Cc: Preeti Murthy <preeti.lkml@gmail.com>, Preeti U Murthy <preeti@linux.vnet.ibm.com>, Viresh Kumar <viresh.kumar@linaro.org>, Frederic Weisbecker <fweisbec@gmail.com>, Fengguang Wu <fengguang.wu@intel.com>, Frederic Weisbecker <frederic@kernel.org>, "Pan, Jacob jun" <jacob.jun.pan@intel.com>, LKML <linux-kernel@vger.kernel.org>, LKP <lkp@01.org>, Peter Zijlstra <peterz@infradead.org>, Zhang Rui <rui.zhang@intel.com> Subject: Re: [PATCH] tick/powerclamp: Remove tick_nohz_idle abuse Date: Thu, 18 Dec 2014 15:43:06 +0100 (CET) [thread overview] Message-ID: <alpine.DEB.2.11.1412181507000.17382@nanos> (raw) In-Reply-To: <20141218140106.GA6323@developer> On Thu, 18 Dec 2014, Eduardo Valentin wrote: > > The real solution is to fix the powerclamp driver by rewriting it with > > a sane concept, but that's beyond the scope of this. > > > > Do you have suggestions on what exactly is the expected rewriting or the > correct sane concepts? There was quite some discussion about this in this very thread. > > So the only solution for now is to remove the calls into the core NOHZ > > code from the powerclamp trainwreck along with the exports. > > > > Fixes: d6d71ee4a14a "PM: Introduce Intel PowerClamp Driver" > > If I got it right, the driver is currently broken due to changes in NOHZ > core. So, does this patch fix power clamp behavior ? The driver has been broken forever. It just worked by chance. Now a very well justified and correct change in the core code exposed that wreckage. So we have 2 choices: 1) Get rid of the abuse and let powerclamp deal with the problem. 2) Revert a correct patch for the sake of a 'works by chance' driver or put hacky workarounds in the core. Either of that will just paper over the real root cause until the next thing breaks in subtle ways. #1 is the only sane decision. We cannot deal with misdesigned driver code in the NOHZ core. > If I got your proposal right, in the end power clamp will be still > broken, but at least won't be abusing NOHZ. Is that what you are > proposing? Yes, the design of powerclamp stays broken, but the NOHZ abuse is gone. powerclamp will work, but it can't benefit from the possible longer idle times anymore. Thanks, tglx
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de> To: lkp@lists.01.org Subject: Re: [PATCH] tick/powerclamp: Remove tick_nohz_idle abuse Date: Thu, 18 Dec 2014 15:43:06 +0100 [thread overview] Message-ID: <alpine.DEB.2.11.1412181507000.17382@nanos> (raw) In-Reply-To: <20141218140106.GA6323@developer> [-- Attachment #1: Type: text/plain, Size: 1626 bytes --] On Thu, 18 Dec 2014, Eduardo Valentin wrote: > > The real solution is to fix the powerclamp driver by rewriting it with > > a sane concept, but that's beyond the scope of this. > > > > Do you have suggestions on what exactly is the expected rewriting or the > correct sane concepts? There was quite some discussion about this in this very thread. > > So the only solution for now is to remove the calls into the core NOHZ > > code from the powerclamp trainwreck along with the exports. > > > > Fixes: d6d71ee4a14a "PM: Introduce Intel PowerClamp Driver" > > If I got it right, the driver is currently broken due to changes in NOHZ > core. So, does this patch fix power clamp behavior ? The driver has been broken forever. It just worked by chance. Now a very well justified and correct change in the core code exposed that wreckage. So we have 2 choices: 1) Get rid of the abuse and let powerclamp deal with the problem. 2) Revert a correct patch for the sake of a 'works by chance' driver or put hacky workarounds in the core. Either of that will just paper over the real root cause until the next thing breaks in subtle ways. #1 is the only sane decision. We cannot deal with misdesigned driver code in the NOHZ core. > If I got your proposal right, in the end power clamp will be still > broken, but at least won't be abusing NOHZ. Is that what you are > proposing? Yes, the design of powerclamp stays broken, but the NOHZ abuse is gone. powerclamp will work, but it can't benefit from the possible longer idle times anymore. Thanks, tglx
next prev parent reply other threads:[~2014-12-18 14:43 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-12-18 10:51 [PATCH] tick/powerclamp: Remove tick_nohz_idle abuse Thomas Gleixner 2014-12-18 10:51 ` Thomas Gleixner 2014-12-18 14:01 ` Eduardo Valentin 2014-12-18 14:01 ` Eduardo Valentin 2014-12-18 14:43 ` Thomas Gleixner [this message] 2014-12-18 14:43 ` Thomas Gleixner 2014-12-18 17:28 ` Preeti U Murthy 2014-12-18 17:28 ` Preeti U Murthy [not found] ` <DD415AA12F8FF042BF4EA69DF123C1478AF91730@ORSMSX101.amr.corp.intel.com> 2014-12-18 19:52 ` Jacob Pan 2014-12-18 19:52 ` Jacob Pan 2014-12-18 21:12 ` Thomas Gleixner 2014-12-18 21:12 ` Thomas Gleixner 2014-12-19 18:39 ` Jacob Pan 2014-12-19 18:39 ` Jacob Pan 2014-12-19 19:56 ` Thomas Gleixner 2014-12-19 19:56 ` Thomas Gleixner 2014-12-20 1:31 ` Preeti U Murthy 2014-12-20 1:31 ` Preeti U Murthy 2014-12-23 2:57 ` Jacob Pan 2014-12-23 2:57 ` Jacob Pan 2014-12-31 5:04 ` Preeti U Murthy 2014-12-31 5:04 ` Preeti U Murthy 2014-12-19 13:09 ` [tip:timers/urgent] " tip-bot for Thomas Gleixner 2014-12-19 13:09 ` tip-bot for Thomas Gleixner
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