On 01/09/2018 10:10 PM, Tejun Heo wrote:
> Hello,
>
> On Tue, Jan 02, 2018 at 07:24:01PM +0100, Michael Kerrisk (man-pages) wrote:
>> 2. We write the string "threaded" to each of the domain invalid
>> cgroups under y, in order to convert them to the type
>> threaded. As a consequence of this step, all threads under
>> the threaded root now have the type threaded and the
>> threaded subtree is now fully usable. The requirement to
>> write "threaded" to each of these cgroups is somewhat cum‐
>> bersome, but allows for possible future extensions to the
>> thread-mode model.
>>
>> ┌─────────────────────────────────────────────────────┐
>> │FIXME │
>> ├─────────────────────────────────────────────────────┤
>> │Re the preceding paragraphs... Are there other rea‐ │
>> │sosn for the (cumbersome) requirement to write │
>> │'threaded' to each of the cgroup.type files in the │
>> │threaded subtrees? Tejun Heo mentioned the follow‐ │
>> │ing: │
>> │ │
>> │ Consistency w/ the cgroups right under the root │
>> │ cgroup. Because they can be both domains and │
>> │ threadroots, we can't switch the children over │
>> │ to thread mode automatically. Doing that for │
>> │ cgroups further down in the hierarchy would be │
>> │ really inconsistent. │
>> │ │
>> │But, it's not clear to me how "Doing that for │
>> │cgroups further down in the hierarchy would be │
>> │really inconsistent", since in the current implemen‐ │
>> │tation, those same thread groups are converted to │
>> │"domain invalid" type. What am I missing? │
>> └─────────────────────────────────────────────────────┘
>
> Yeah, I was confused with an earlier varient where we were marking
> threaded domains instead of threaded roots. It's mostly about future
> extensibility (especially as Waiman was proposing related changes
> there) and not doing things automatically / recursively if possible.
>
> Looks good to me.
One more thing. I added the following sentence to the text:
The cgroup.threads file is writable only for the cgroups inside a
threaded subtree.
Can you confirm that that is correct, please.
Cheers,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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