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Groups > linux.kernel > #1537110 > unrolled thread
| Started by | Pavel Machek <pavel@ucw.cz> |
|---|---|
| First post | 2016-12-06 18:00 +0100 |
| Last post | 2016-12-09 00:00 +0100 |
| Articles | 6 — 2 participants |
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Re: [PATCH 2/5] x86: remove idle_notifier Pavel Machek <pavel@ucw.cz> - 2016-12-06 18:00 +0100
Re: [PATCH 2/5] x86: remove idle_notifier Thomas Gleixner <tglx@linutronix.de> - 2016-12-07 12:50 +0100
Re: [PATCH 2/5] x86: remove idle_notifier Pavel Machek <pavel@ucw.cz> - 2016-12-07 14:50 +0100
Re: [PATCH 2/5] x86: remove idle_notifier Thomas Gleixner <tglx@linutronix.de> - 2016-12-08 10:30 +0100
Re: [PATCH 2/5] x86: remove idle_notifier Pavel Machek <pavel@ucw.cz> - 2016-12-08 23:10 +0100
Re: [PATCH 2/5] x86: remove idle_notifier Thomas Gleixner <tglx@linutronix.de> - 2016-12-09 00:00 +0100
| From | Pavel Machek <pavel@ucw.cz> |
|---|---|
| Date | 2016-12-06 18:00 +0100 |
| Subject | Re: [PATCH 2/5] x86: remove idle_notifier |
| Message-ID | <sLrfX-4AN-11@gated-at.bofh.it> |
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Hi! > From: Len Brown <len.brown@intel.com> > > Upon removal of the i7300_idle driver, the idle_notifer is unused. Actually... do we want to keep this this one? There's "cpu is loaded" led trigger, which is implemented on arm but not on x86. I tried to patch process.c, but this would be easier (and does not require new hooks). Does that make sense? Best regards, Pavel > Signed-off-by: Len Brown <len.brown@intel.com> > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2016-12-07 12:50 +0100 |
| Message-ID | <sLITv-80n-5@gated-at.bofh.it> |
| In reply to | #1537110 |
On Tue, 6 Dec 2016, Pavel Machek wrote: > > From: Len Brown <len.brown@intel.com> > > > > Upon removal of the i7300_idle driver, the idle_notifer is unused. > > Actually... do we want to keep this this one? There's "cpu is loaded" > led trigger, which is implemented on arm but not on x86. > > I tried to patch process.c, but this would be easier (and does not > require new hooks). > > Does that make sense? No. Notifiers are crap. I assume this LED thing is just for entertainment purposes as I cannot figure out why it would be useful. ARM has it does not qualify as useful. Thanks, tglx
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| From | Pavel Machek <pavel@ucw.cz> |
|---|---|
| Date | 2016-12-07 14:50 +0100 |
| Message-ID | <sLKLD-Il-11@gated-at.bofh.it> |
| In reply to | #1537694 |
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On Wed 2016-12-07 12:46:12, Thomas Gleixner wrote: > On Tue, 6 Dec 2016, Pavel Machek wrote: > > > From: Len Brown <len.brown@intel.com> > > > > > > Upon removal of the i7300_idle driver, the idle_notifer is unused. > > > > Actually... do we want to keep this this one? There's "cpu is loaded" > > led trigger, which is implemented on arm but not on x86. > > > > I tried to patch process.c, but this would be easier (and does not > > require new hooks). > > > > Does that make sense? > > No. Notifiers are crap. > > I assume this LED thing is just for entertainment purposes as I cannot > figure out why it would be useful. ARM has it does not qualify as useful. Well, on low-speed systems, that led is actually quite important. You know if your keypress was registered, and CPU is just slow, or if you need to press it again. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2016-12-08 10:30 +0100 |
| Message-ID | <sM3bz-4nK-1@gated-at.bofh.it> |
| In reply to | #1537759 |
On Wed, 7 Dec 2016, Pavel Machek wrote: > On Wed 2016-12-07 12:46:12, Thomas Gleixner wrote: > > On Tue, 6 Dec 2016, Pavel Machek wrote: > > > > From: Len Brown <len.brown@intel.com> > > > > > > > > Upon removal of the i7300_idle driver, the idle_notifer is unused. > > > > > > Actually... do we want to keep this this one? There's "cpu is loaded" > > > led trigger, which is implemented on arm but not on x86. > > > > > > I tried to patch process.c, but this would be easier (and does not > > > require new hooks). > > > > > > Does that make sense? > > > > No. Notifiers are crap. > > > > I assume this LED thing is just for entertainment purposes as I cannot > > figure out why it would be useful. ARM has it does not qualify as useful. > > Well, on low-speed systems, that led is actually quite important. You > know if your keypress was registered, and CPU is just slow, or if you > need to press it again. I'm dealing with low-speed systems for 20 years now and that LED was never important for me, quite the contrary, it's annoying to have the extra work in the idle wakeup path which causes extra pointless latency. If you can't figure out your keypress lag without that LED then feel free to patch your own kernel, but stop trying to impose that nonsense on everyone. Thanks, tglx
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| From | Pavel Machek <pavel@ucw.cz> |
|---|---|
| Date | 2016-12-08 23:10 +0100 |
| Message-ID | <sMf33-3iT-13@gated-at.bofh.it> |
| In reply to | #1538401 |
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On Thu 2016-12-08 10:18:13, Thomas Gleixner wrote: > On Wed, 7 Dec 2016, Pavel Machek wrote: > > On Wed 2016-12-07 12:46:12, Thomas Gleixner wrote: > > > On Tue, 6 Dec 2016, Pavel Machek wrote: > > > > > From: Len Brown <len.brown@intel.com> > > > > > > > > > > Upon removal of the i7300_idle driver, the idle_notifer is unused. > > > > > > > > Actually... do we want to keep this this one? There's "cpu is loaded" > > > > led trigger, which is implemented on arm but not on x86. > > > > > > > > I tried to patch process.c, but this would be easier (and does not > > > > require new hooks). > > > > > > > > Does that make sense? > > > > > > No. Notifiers are crap. > > > > > > I assume this LED thing is just for entertainment purposes as I cannot > > > figure out why it would be useful. ARM has it does not qualify as useful. > > > > Well, on low-speed systems, that led is actually quite important. You > > know if your keypress was registered, and CPU is just slow, or if you > > need to press it again. > > I'm dealing with low-speed systems for 20 years now and that LED was never > important for me, quite the contrary, it's annoying to have the extra work > in the idle wakeup path which causes extra pointless latency. If you can't > figure out your keypress lag without that LED then feel free to patch your > own kernel, but stop trying to impose that nonsense on everyone. The kernel already has the hooks, and they did not seem to bother anyone. Arm already has the functionality, and it is useful. You may not care, but so what. Leds are broken on x86, plain and simple. Perhaps that should not be your decision? Feel free to patch it out of your kernel. Or feel free to argue that it needs to be removed from arm. But having unneccessary differences between architectures is just ugly. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2016-12-09 00:00 +0100 |
| Message-ID | <sMfPr-3Bd-3@gated-at.bofh.it> |
| In reply to | #1538911 |
On Thu, 8 Dec 2016, Pavel Machek wrote: > On Thu 2016-12-08 10:18:13, Thomas Gleixner wrote: > > I'm dealing with low-speed systems for 20 years now and that LED was never > > important for me, quite the contrary, it's annoying to have the extra work > > in the idle wakeup path which causes extra pointless latency. If you can't > > figure out your keypress lag without that LED then feel free to patch your > > own kernel, but stop trying to impose that nonsense on everyone. > > The kernel already has the hooks, and they did not seem to bother > anyone. The have bothered a lot of people up to the point where we could remove them, simply because they are pointless ballast and overhead in the wake from idle path. > Arm already has the functionality, and it is useful. You may > not care, but so what. Leds are broken on x86, plain and simple. BlinkenLEDs for idle were never available on x86 to begin with, so they can't be broken. Aisde of that the vast majority of x86 systems simply do not have LEDs which are accessible from that context. So just to support a very questionable use case with a very limited usefulness you want to impose extra code into a code path which is already known to be too heavy weight and people working on it to reduce the overhead. > Perhaps that should not be your decision? Feel free to complain to Linus. My maintainer decision stands. > Feel free to patch it out of your kernel. Or feel free to argue that it > needs to be removed from arm. But having unneccessary differences between > architectures is just ugly. Following that argumentation would require to add this to the core idle code, so _ALL_ architetures have access to this, but that got turned down by the core maintainers a more than a year ago for the very same reason. Thanks, tglx
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