Re: [PATCH v2 00/11] zsmalloc: redesign object alloc API

[Yosry Ahmed]

On Mon, Nov 9, 2026 at 9:48 PM Sergey Senozhatsky
<senozhatsky@xxxxxxxxxxxx> wrote:
>
> Both zram and zswap already have per-entry structures that store zsmalloc
> handles, so allocating a separate handle_cachep object per stored page is
> redundant.  This series embeds struct zs_handle directly into zram and
> zswap entries and drops handle_cachep, saving 8 bytes and a slab
> alloc/free per stored object (2MB per 1GB of swapped out 4K pages).
>
> It also folds zs_malloc() and zs_obj_write() into zs_store() so we don't
> take pool->lock and look up object location again right after allocation.
>
> A simple zram test on a 24-vCPU VM
> ==================================
> 165 fewer kernel instructions and 0.7-1.8% fewer kernel cycles per write;
> lz4 single writer +2.3% IOPS / -2.6% average latency;
> 24 writers +0.9-+1.0% IOPS; no regressions.
> Memory: 8 bytes less per stored page.
>
> v1 -> v2:
> -- addressed Yosry's v1 feedback (too lengthy to mention here, Yosry
>    posted over a million comments, or something very close to that):
>    split-ed some patches, squashed the other ones, added handle
>    alignment run-time check, added 0 PFN defense, etc.

I will take this as a good thing :p