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

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Message-ID: <PH7PR11MB8121E83F0EBE9BEF5F777466C93DA@PH7PR11MB8121.namprd11.prod.outlook.com>
Date: Fri, 22 Aug 2025 21:58:13 +0000
From: "Sridhar, Kanchana P" <kanchana.p.sridhar@...el.com>
To: Nhat Pham <nphamcs@...il.com>
CC: Herbert Xu <herbert@...dor.apana.org.au>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>,
	"hannes@...xchg.org" <hannes@...xchg.org>, "yosry.ahmed@...ux.dev"
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	<akpm@...ux-foundation.org>, "senozhatsky@...omium.org"
	<senozhatsky@...omium.org>, "linux-crypto@...r.kernel.org"
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	<ardb@...nel.org>, "ebiggers@...gle.com" <ebiggers@...gle.com>,
	"surenb@...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>, "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: Nhat Pham <nphamcs@...il.com>
> Sent: Friday, August 22, 2025 2:48 PM
> To: Sridhar, Kanchana P <kanchana.p.sridhar@...el.com>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>; linux-
> kernel@...r.kernel.org; linux-mm@...ck.org; hannes@...xchg.org;
> yosry.ahmed@...ux.dev; 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 Fri, Aug 22, 2025 at 12:31 PM Sridhar, Kanchana P
> <kanchana.p.sridhar@...el.com> wrote:
> >
> >
> > > -----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.
> 
> I think he meant stored it as a static unsigned int field, rather than
> a function pointer (i.e dynamic) like this.

I see. Got it! Sure, I will make this change in v12. Thanks Nhat!

Best regards,
Kanchana

> 
> Does batch size ever change at runtime?