Re: [Devel] [PATCH 0/5] Kernel memory accounting container (v5)

[Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>]

Paul Menage wrote:
> On 10/2/07, Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> wrote:
>> Such a lookup would require a hastable or something similar. We already
>> have such a bad experience (with OpenVZ RSS fractions accounting for
>> example). Hash lookups imply the CPU caches screwup and hurt the performance.
>> See also the comment below.
> 
> I think you could do it with an array lookup if you assigned an index
> to each cache as it was created, and used that as an offset into a
> per-cgroup array.
> 
>> I thought the same some time ago and tried to make a per-beancounter kmem
>> caches. The result was awful - the memory waste was much larger than in the
>> case of pointer-per-object approach.
> 
> OK, fair enough.
> 
> Was this with a large number of bean counters? I imagine that with a
> small number, the waste might be rather more reasonable.

Yup. I do not remember the exact number, but this model didn't scale
well enough in respect to the number of beancounters.

> Paul
>