Messages in this thread | | | Date | Fri, 25 Oct 2019 04:06:23 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH 1/2] cgroup: Add generation number with cgroup id |
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Hello,
On Fri, Oct 25, 2019 at 05:30:35PM +0900, Namhyung Kim wrote: > > Any chance I can persuade you into making this conversion? idr is > > exactly the wrong data structure to use for cyclic allocations. We've > > been doing it mostly for historical reasons but I really hope we can > > move away from it. These lookups aren't in super hot paths and doing > > locked lookups should be fine. > > As you know, it entails change in kernfs id and its users. > And I really want to finish the perf cgroup sampling work first. > Can I work on this after the perf work is done?
Sure, but I think we should get the userland visible behaviors right. Ignoring implementation details:
* cgroup vs. css IDs doesn't matter for now. css IDs aren't visible to userland anyway and it could be that keeping using idr as-is or always using 64bit IDs is the better solution for them.
* On 32bit ino setups, 32bit ino + gen as cgroup and export fs IDs.
* On 64bit ino setups, 64bit unique ino (allocated whichever way) + 0 gen as cgroup and export fs IDs.
Thanks.
-- tejun
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