3.0.12 - unregister_pernet_gen_subsys hogging whole system

3.0.12 - unregister_pernet_gen_subsys hogging whole system

[Nikola Ciprich]

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Hi,

after updating one of our servers to 3.0.12 kernel, it became painfully slow (actually
it's almost unusable).

trying perf top, I see following:

            27465.00 - 59.8% : unregister_pernet_gen_subsys
             3144.00 -  6.8% : __start_notes
             1211.00 -  2.6% : swiotlb_sync_sg
             1155.00 -  2.5% : swiotlb_unmap_sg_attrs
              621.00 -  1.4% : pci_pm_init
              565.00 -  1.2% : swiotlb_map_sg_attrs
              503.00 -  1.1% : cgroup_attach_task

I wasn't too successfull trying to find something related, so I'd like to ask,
which subsystem might be calling unregister_pernet_gen_subsys and why?
I guess this is certaingly a bug... Could somebody please have a look at this?
I'll provide all debugging information I can if needed..

thanks a lot in advance

with best regards

nik

-- 
-------------------------------------
Ing. Nikola CIPRICH
LinuxBox.cz, s.r.o.
28. rijna 168, 709 01 Ostrava

tel.:   +420 596 603 142
fax:    +420 596 621 273
mobil:  +420 777 093 799
www.linuxbox.cz

mobil servis: +420 737 238 656
email servis: servis@linuxbox.cz
-------------------------------------

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Re: 3.0.12 - unregister_pernet_gen_subsys hogging whole system

[Nikola Ciprich]

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> after updating one of our servers to 3.0.12 kernel, it became painfully slow (actually
> it's almost unusable).
> 
> trying perf top, I see following:
> 
>             27465.00 - 59.8% : unregister_pernet_gen_subsys
>              3144.00 -  6.8% : __start_notes
>              1211.00 -  2.6% : swiotlb_sync_sg
>              1155.00 -  2.5% : swiotlb_unmap_sg_attrs
>               621.00 -  1.4% : pci_pm_init
>               565.00 -  1.2% : swiotlb_map_sg_attrs
>               503.00 -  1.1% : cgroup_attach_task

crap, I was using too old perf binary - that might be reason why I wasn't able
to find any evidence of unregister_pernet_gen_subsys for 3.x kernels :)
I switched to 3.0.13 now (and actual perf) and it seems better..
Should the problem reappear, I'll report it..
sorry for the fuzz..
n.


> 
> I wasn't too successfull trying to find something related, so I'd like to ask,
> which subsystem might be calling unregister_pernet_gen_subsys and why?
> I guess this is certaingly a bug... Could somebody please have a look at this?
> I'll provide all debugging information I can if needed..
> 
> thanks a lot in advance
> 
> with best regards
> 
> nik
> 
> -- 
> -------------------------------------
> Ing. Nikola CIPRICH
> LinuxBox.cz, s.r.o.
> 28. rijna 168, 709 01 Ostrava
> 
> tel.:   +420 596 603 142
> fax:    +420 596 621 273
> mobil:  +420 777 093 799
> www.linuxbox.cz
> 
> mobil servis: +420 737 238 656
> email servis: servis@linuxbox.cz
> -------------------------------------



-- 
-------------------------------------
Ing. Nikola CIPRICH
LinuxBox.cz, s.r.o.
28. rijna 168, 709 01 Ostrava

tel.:   +420 596 603 142
fax:    +420 596 621 273
mobil:  +420 777 093 799

www.linuxbox.cz

mobil servis: +420 737 238 656
email servis: servis@linuxbox.cz
-------------------------------------

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