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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <SJ2PR11MB84728C0DFE406F04EE7C617CC9A2A@SJ2PR11MB8472.namprd11.prod.outlook.com>
Date: Mon, 8 Dec 2025 04:33:19 +0000
From: "Sridhar, Kanchana P" <kanchana.p.sridhar@...el.com>
To: Herbert Xu <herbert@...dor.apana.org.au>
CC: Yosry Ahmed <yosry.ahmed@...ux.dev>, SeongJae Park <sj@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>, "hannes@...xchg.org"
	<hannes@...xchg.org>, "nphamcs@...il.com" <nphamcs@...il.com>,
	"chengming.zhou@...ux.dev" <chengming.zhou@...ux.dev>,
	"usamaarif642@...il.com" <usamaarif642@...il.com>, "ryan.roberts@....com"
	<ryan.roberts@....com>, "21cnbao@...il.com" <21cnbao@...il.com>,
	"ying.huang@...ux.alibaba.com" <ying.huang@...ux.alibaba.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"senozhatsky@...omium.org" <senozhatsky@...omium.org>, "kasong@...cent.com"
	<kasong@...cent.com>, "linux-crypto@...r.kernel.org"
	<linux-crypto@...r.kernel.org>, "davem@...emloft.net" <davem@...emloft.net>,
	"clabbe@...libre.com" <clabbe@...libre.com>, "ardb@...nel.org"
	<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 v13 22/22] mm: zswap: Batched zswap_compress() with
 compress batching of large folios.


> -----Original Message-----
> From: Herbert Xu <herbert@...dor.apana.org.au>
> Sent: Sunday, December 7, 2025 8:24 PM
> To: Sridhar, Kanchana P <kanchana.p.sridhar@...el.com>
> Cc: Yosry Ahmed <yosry.ahmed@...ux.dev>; SeongJae Park <sj@...nel.org>;
> linux-kernel@...r.kernel.org; linux-mm@...ck.org; hannes@...xchg.org;
> 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; kasong@...cent.com; 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 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,
> --
> 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