linux-kernel - RE: [PATCH v11 18/24] crypto: acomp - Add crypto_acomp_batch

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Message-ID: <PH7PR11MB81210ABFD0BF9F73214080E8C93DA@PH7PR11MB8121.namprd11.prod.outlook.com>
Date: Fri, 22 Aug 2025 19:31:11 +0000
From: "Sridhar, Kanchana P" <kanchana.p.sridhar@...el.com>
To: Herbert Xu <herbert@...dor.apana.org.au>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>, "hannes@...xchg.org"
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	"Feghali, Wajdi K" <wajdi.k.feghali@...el.com>, "Gopal, Vinodh"
	<vinodh.gopal@...el.com>, "Sridhar, Kanchana P"
	<kanchana.p.sridhar@...el.com>
Subject: RE: [PATCH v11 18/24] crypto: acomp - Add crypto_acomp_batch_size()
 to get an algorithm's batch-size.


> -----Original Message-----
> From: Herbert Xu <herbert@...dor.apana.org.au>
> Sent: Thursday, August 14, 2025 10:29 PM
> To: Sridhar, Kanchana P <kanchana.p.sridhar@...el.com>
> Cc: linux-kernel@...r.kernel.org; linux-mm@...ck.org;
> hannes@...xchg.org; yosry.ahmed@...ux.dev; nphamcs@...il.com;
> chengming.zhou@...ux.dev; usamaarif642@...il.com;
> ryan.roberts@....com; 21cnbao@...il.com;
> ying.huang@...ux.alibaba.com; akpm@...ux-foundation.org;
> senozhatsky@...omium.org; linux-crypto@...r.kernel.org;
> davem@...emloft.net; clabbe@...libre.com; ardb@...nel.org;
> ebiggers@...gle.com; surenb@...gle.com; Accardi, Kristen C
> <kristen.c.accardi@...el.com>; Gomes, Vinicius <vinicius.gomes@...el.com>;
> Feghali, Wajdi K <wajdi.k.feghali@...el.com>; Gopal, Vinodh
> <vinodh.gopal@...el.com>
> Subject: Re: [PATCH v11 18/24] crypto: acomp - Add
> crypto_acomp_batch_size() to get an algorithm's batch-size.
> 
> On Thu, Jul 31, 2025 at 09:36:36PM -0700, Kanchana P Sridhar wrote:
> >
> > diff --git a/include/crypto/internal/acompress.h
> b/include/crypto/internal/acompress.h
> > index ffffd88bbbad3..2325ee18e7a10 100644
> > --- a/include/crypto/internal/acompress.h
> > +++ b/include/crypto/internal/acompress.h
> > @@ -28,6 +28,8 @@
> >   *
> >   * @compress:	Function performs a compress operation
> >   * @decompress:	Function performs a de-compress operation
> > + * @get_batch_size:	Maximum batch-size for batching
> compress/decompress
> > + *			operations.
> >   * @init:	Initialize the cryptographic transformation object.
> >   *		This function is used to initialize the cryptographic
> >   *		transformation object. This function is called only once at
> > @@ -46,6 +48,7 @@
> >  struct acomp_alg {
> >  	int (*compress)(struct acomp_req *req);
> >  	int (*decompress)(struct acomp_req *req);
> > +	unsigned int (*get_batch_size)(void);
> 
> I can't imagine a situation where this needs to be dynamic.
> Please just make it a static value rather than a callback function.

Hi Herbert,

I am not sure I understand.. Kernel users such as zswap/zram need to query
the algorithm to get the maximum supported batch-size so they can allocate
resources for dst buffers. The get_batch_size() callback and associated
crypto_acomp_batch_size() wrapper help accomplish this.

Can you please clarify what you mean by "static value"?

Thanks,
Kanchana

> 
> Thanks,
> --
> Email: Herbert Xu <herbert@...dor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt