* Steven Rostedt <rost...@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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