Messages in this thread | | | Date | Mon, 27 Apr 2020 16:21:01 +0000 (UTC) | From | Christopher Lameter <> | Subject | Re: [PATCH v3 04/19] mm: slub: implement SLUB version of obj_to_index() |
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On Fri, 24 Apr 2020, Roman Gushchin wrote:
> > The patch seems to only use it for setup and debugging? It is used for > > every "accounted" allocation???? Where? And what is an "accounted" > > allocation? > > > > > > Please, take a look at the whole series: > https://lore.kernel.org/linux-mm/20200422204708.2176080-1-guro@fb.com/T/#t > > I'm sorry, I had to cc you directly for the whole thing. Your feedback > will be highly appreciated. > > It's used to calculate the offset of the memcg pointer for every slab > object which is charged to a memory cgroup. So it must be quite hot.
Ahh... Thanks. I just looked at it.
You need this because you have a separate structure attached to a page that tracks membership of the slab object to the cgroup. This is used to calculate the offset into that array....
Why do you need this? Just slap a pointer to the cgroup as additional metadata onto the slab object. Is that not much simpler, safer and faster?
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