From: Yosry Ahmed <yosryahmed@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Seth Jennings <sjenning@redhat.com>,
Dan Streetman <ddstreet@ieee.org>,
Vitaly Wool <vitaly.wool@konsulko.com>,
Nhat Pham <nphamcs@gmail.com>,
Domenico Cerasuolo <cerasuolodomenico@gmail.com>,
Yu Zhao <yuzhao@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: zswap: support exclusive loads
Date: Tue, 30 May 2023 16:56:49 -0700 [thread overview]
Message-ID: <CAJD7tkb3GO7yiYp4NHApyRHyg_kzaPuMQPvkvS0aUzUHkPkNzg@mail.gmail.com> (raw)
In-Reply-To: <20230530235447.GB102494@cmpxchg.org>
On Tue, May 30, 2023 at 4:54 PM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> On Tue, May 30, 2023 at 09:02:51PM +0000, Yosry Ahmed wrote:
> > @@ -216,8 +216,13 @@ int __frontswap_load(struct page *page)
> >
> > /* Try loading from each implementation, until one succeeds. */
> > ret = frontswap_ops->load(type, offset, page);
> > - if (ret == 0)
> > + if (ret == 0) {
> > inc_frontswap_loads();
> > + if (frontswap_ops->exclusive_loads) {
> > + SetPageDirty(page);
> > + __frontswap_clear(sis, offset);
> > + }
>
> Somewhat tangential, but is there still a point to the frontswap
> layer? It seems usecases other than zswap have never materialized, at
> least not in tree. Life would be a lot easier if we were to just
> hardcode the zswap callbacks in the swap functions.
>
> It's not the patch's fault, but it highlights the boiler plate the
> indirection causes. ->load() already has the page and could just dirty
> it directly. Instead now both layers have to handle invalidation,
> which is a vector for bugs.
>
> Can somebody think of reasons to keep it? If not, I'd take a stab at
> removing it.
I was intending to eventually remove it as part of the swap
abstraction proposal I am working on, but this will take some time. If
you want to remove it now, even better :)
next prev parent reply other threads:[~2023-05-30 23:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 21:02 [PATCH] mm: zswap: support exclusive loads Yosry Ahmed
2023-05-30 21:15 ` Andrew Morton
2023-05-30 21:20 ` Yosry Ahmed
2023-05-30 23:54 ` Johannes Weiner
2023-05-30 23:56 ` Yosry Ahmed [this message]
2023-05-31 6:00 ` Christoph Hellwig
2023-06-07 14:13 ` Johannes Weiner
2023-06-07 16:33 ` Yosry Ahmed
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