| Re: [PATCH] fix bad behavior in use_hierarchy file [message #46996 is a reply to message #46969] |
Tue, 26 June 2012 17:55   |
Tejun Heo
Messages: 184
Registered: November 2006
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Senior Member |
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Hello,
On Tue, Jun 26, 2012 at 09:56:53AM +0200, Michal Hocko wrote:
> [Adding Ying to CC - they are using hierarchies AFAIU in their workloads]
Ooh, I'm they. :) Asking around.... okay, so google does use
.use_hierarchy but it's a tree-wide thing and would be perfectly happy
with a global switch.
> On Mon 25-06-12 13:49:08, Tejun Heo wrote:
> [...]
> > A bit of delta but is there any chance we can either deprecate
> > .use_hierarhcy or at least make it global toggle instead of subtree
> > thing?
>
> So what you are proposing is to have all subtrees of the root either
> hierarchical or not, right?
Yeap. Just make it a global switch. Probably determined on mount
time.
> > This seems needlessly complicated. :(
>
> Toggle wouldn't help much I am afraid. We would still have to
> distinguish (non)hierarchical cases. And I am not sure we can make
> everything hierarchical easily.
I'm kinda confused by this paragraph. What do you mean by "wouldn't
help much"? Do you mean in terms of complexity?
> Most users (from my experience) ignored use_hierarchy for some reasons
> and the end results might be really unexpected for them if they used
> deeper subtrees (which might be needed due to combination with other
> controller(s)).
Oh yeah, we can't change the default behavior like that. The
transition should be a lot more gradual. Even if making
.use_hierarchy doesn't help much in terms of reducing complexity right
now, it would at least allow us to weed out and prevent wacky woo-hoo
mom-look-at-what-I-can-do configurations which will be a lot more
difficult to deal with for both us and such users (if we end up
forcing hierarchy).
Thanks.
--
tejun
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