linux-kernel - Re: [RFC PATCH v3 0/7] slub: Delay freezing of CPU partial slabs

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Date:   Mon, 30 Oct 2023 12:25:19 -0700 (PDT)
From:   Christoph Lameter <cl@...ux.com>
To:     Chengming Zhou <chengming.zhou@...ux.dev>
cc:     penberg@...nel.org, rientjes@...gle.com, iamjoonsoo.kim@....com,
        akpm@...ux-foundation.org, vbabka@...e.cz,
        roman.gushchin@...ux.dev, 42.hyeyoo@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Chengming Zhou <zhouchengming@...edance.com>
Subject: Re: [RFC PATCH v3 0/7] slub: Delay freezing of CPU partial slabs

On Sat, 28 Oct 2023, Chengming Zhou wrote:

> 2. But for full slab (slab->freelist == NULL), PG_workingset is not much useful, we don't
>   safely know whether it's used as the cpu slab or not just from this flag. So __slab_free()
>   still rely on the "frozen" bit to know it.
>
> 3. And the maintaining of "frozen" has no extra cost now, since it's changed together with "freelist"
>   and other counter using cmpxchg, we already have the cmpxchg when start to use a slab as the cpu slab.
>
> Maybe I missed something, I don't know how to drop the frozen flag.


Maybe frozen is now = PG_Workingset | cmpxchg-frozen?