Re: [PATCH v13 22/22] mm: zswap: Batched zswap_compress() with compress batching of large folios.

[Yosry Ahmed]

On Tue, Dec 09, 2025 at 10:32:20AM +0800, Herbert Xu wrote:
> On Tue, Dec 09, 2025 at 01:15:02AM +0000, Yosry Ahmed wrote:
> > 
> > Just to clarify, does this mean that zswap can pass a batch of (eight)
> > pages to the acomp API, and get the results for the batch uniformly
> > whether or not the underlying compressor supports batching?
> 
> Correct.  In fact I'd like to remove the batch size exposure to zswap
> altogether.  zswap should just pass along whatever maximum number of
> pages that is convenient to itself.

I think exposing the batch size is still useful as a hint for zswap. In
the current series, zswap allocates as many per-CPU buffers as the
compressor's batch size, so no extra buffers for non-batching
compressors (including SW compressors).

If we use the same batch size regardless, we'll have to always allocate
8 (or N) per-CPU buffers, for little to no benefit on non-batching
compressors.

So we still want the batch size on the zswap side, but we want the
crypto API to be uniform whether or not the compressor supports
batching.

> 
> Cheers,
> -- 
> Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Home Page: http://gondor.apana.org.au/~herbert/
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