Re: [PATCH] slub: avoid scanning all partial slabs in get_slabinfo()

[Chengming Zhou]

On 2024/2/23 11:02, Christoph Lameter (Ampere) wrote:
> On Thu, 22 Feb 2024, Chengming Zhou wrote:
> 
>> Anyway, I put the code below for discussion...
> 
> Can we guestimate the free objects based on the number of partial slabs. That number is available.
> 

Yeah, the number of partial slabs is easy to know, but I can't think of a way to
estimate the free objects, since __slab_free() is just double cmpxchg in most cases.

> How accurate need the accounting be? We also have fuzzy accounting in the VM counters.

Maybe not need to be very accurate, some delay/fuzzy should be acceptable.

Another direction I think is that we don't distinguish slabs on cpu partial list or
slabs on node partial list anymore (different with current behavior).

Now we have three scopes:
1. SL_ALL: include all slabs
2. SL_PARTIAL: only include partial slabs on node
3. SL_CPU: only include partail slabs on cpu and the using cpu slab

If we change SL_PARTIAL to mean all partial slabs, it maybe simpler.

Thanks.