Messages in this thread | | | Date | Thu, 7 Feb 2013 12:10:25 +0100 | From | Ingo Molnar <> | Subject | Re: [ANNOUNCE] 3.8-rc6-nohz4 |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> I'll reply to this as I come up with comments. > > First thing is, don't call it NO_HZ_FULL. A better name would > be NO_HZ_CPU. I would like to reserve NO_HZ_FULL when we > totally remove jiffies :-)
I don't think we want yet another config option named in a weird way.
What we want instead is to just split NO_HZ up into its conceptual parts:
CONFIG_NO_HZ_IDLE CONFIG_NO_HZ_USER_SPACE CONFIG_NO_HZ_KERNEL_SPACE
Where the current status quo is NO_HZ_IDLE=y, and Frederic is about to introduce NO_HZ_USER_SPACE=y. When jiffies get removed we get NO_HZ_KERNEL_SPACE=y.
The 'CONFIG_NO_HZ' meta-option, which we should leave for easy configurability and for compatibility, should get us the currently recommended default, which for the time being might be:
CONFIG_NO_HZ_IDLE=y # CONFIG_NO_HZ_USER_SPACE is disabled
Btw., you could add CONFIG_NO_HZ_KERNEL_SPACE right away, just keep it false all the time. That would document our future plans pretty well.
Once CONFIG_NO_HZ_USER_SPACE is proven problem-free, we might default to:
CONFIG_NO_HZ_IDLE=y CONFIG_NO_HZ_USER_SPACE=y
The goal is to have this in the distant future:
CONFIG_NO_HZ=y
CONFIG_NO_HZ_IDLE=y CONFIG_NO_HZ_USER_SPACE=y CONFIG_NO_HZ_KERNEL_SPACE=y
And eventually we might even be able to get rid of all the 3 variants, and only offer full-on/off.
Agreed?
Thanks,
Ingo
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