Messages in this thread | | | Date | Tue, 17 Jan 2017 23:23:14 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] ARM: smp: Remove CPU: shutdown notice |
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On Tue, Jan 17, 2017 at 03:07:12PM -0800, Florian Fainelli wrote: > This message is not particularly informative, and is not paired with an > identical message when a CPU is brought online. Finally, it slows the > CPU hotplug path down, thus allowing less CPU hotplug operations per > second. Just remove it.
CPU hotplug isn't a fast operation anyway - it's also fairly disruptive in that it uses stop_machine() to halt activity everywhere while taking the CPU offline.
If you're worried about a single printk slowing things down, it sounds like you're doing something wrong here - maybe you should be using cpuidle for power management rather than trying to make CPU hotplug do that for you?
A rapidly changing CPU hotplug state has other side effects - such as reading /proc/interrupts is meaningless, because as soon as you've read it the CPUs could have changed. It also makes a farce of spreading interrupts over the available CPUs.
All in all, I don't think this is a good idea...
-- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.
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