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

["Sridhar, Kanchana P" <kanchana.p.sridhar@intel.com>]

> -----Original Message-----
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Sent: Sunday, December 7, 2025 8:24 PM
> To: Sridhar, Kanchana P <kanchana.p.sridhar@intel.com>
> Cc: Yosry Ahmed <yosry.ahmed@linux.dev>; SeongJae Park <sj@kernel.org>;
> linux-kernel@vger.kernel.org; linux-mm@kvack.org; hannes@cmpxchg.org;
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> Kristen C <kristen.c.accardi@intel.com>; Gomes, Vinicius
> <vinicius.gomes@intel.com>; Feghali, Wajdi K <wajdi.k.feghali@intel.com>;
> Gopal, Vinodh <vinodh.gopal@intel.com>
> Subject: Re: [PATCH v13 22/22] mm: zswap: Batched zswap_compress() with
> compress batching of large folios.
> 
> On Mon, Dec 08, 2025 at 04:17:38AM +0000, Sridhar, Kanchana P wrote:
> >
> > I see. So the way my patch-set tries to standardize batching in
> > zswap_compress() is to call it with a batch of 8 pages, regardless of batching
> > or non-batching compressors. In zswap_compress(), I presently iterate
> > through each page in the batch for sequential processing for non-batching
> > compressors whose batch size is 1. For batching compressors, the iteration
> > happens just once: the whole batch is compressed in one call to
> > crypto_acomp_compress().
> 
> Oh I wasn't aware of this.  In that case there is no need for me
> to delay the next step and we can do it straight away.

Sure, makes sense, thanks!

> 
> I had thought that the batch size was to limit the batching size
> to acomp.  But if it's not, perhaps we can remove the batch size
> exposure altogether.  IOW it would only be visible internally to
> the acomp API while the users such as zswap would simply batch
> things in whatever size that suits them.

Yes, I think this can be done. In case zswap sends a batch that is not
an integral multiple of the acomp algorithm's batch-size, we might
have to trade-off one sub-optimal batch (fewer pages than the alg's
batch-size) for a cleaner solution.

Thanks,
Kanchana

> 
> Thanks,
> --
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