From: Andrew Morton <akpm@linux-foundation.org>
To: Evan Green <evgreen@chromium.org>
Cc: David Hildenbrand <david@redhat.com>,
Michal Hocko <mhocko@suse.com>, Pavel Machek <pavel@ucw.cz>,
linux-api@vger.kernel.org, Alex Shi <alexs@kernel.org>,
Alistair Popple <apopple@nvidia.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Miaohe Lin <linmiaohe@huawei.com>,
Minchan Kim <minchan@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH v4] mm: Enable suspend-only swap spaces
Date: Tue, 27 Jul 2021 14:18:32 -0700 [thread overview]
Message-ID: <20210727141832.86695e7181eb10c6e8fd0191@linux-foundation.org> (raw)
In-Reply-To: <CAE=gft7567-2Lq7raJKrOpQ8UAvXTFWwPci=_GCRPET3nS=9SA@mail.gmail.com>
On Tue, 27 Jul 2021 09:31:33 -0700 Evan Green <evgreen@chromium.org> wrote:
> > Pavel just mentioned uswsusp, and I wonder if it would be a possible
> > alternative to this patch.
>
> I think you're right that it would be possible to isolate the
> hibernate image with uswsusp if you avoid using the SNAPSHOT_*SWAP*
> ioctls. But I'd expect performance to suffer noticeably, since now
> every page is making a round trip out to usermode and back. I'd still
> very much use the HIBERNATE_ONLY flag if it were accepted, I think
> there's value to it.
The uswsusp option makes your patch a performance optimization rather
than a feature-add. And we do like to see quantitative testing results
when considering a performance optimization. Especially when the
performance optimization is a bit icky, putting special-case testing
all over the place, maintenance cost, additional testing effort, etc.
I do think that diligence demands that we quantify the difference. Is
this a thing you can help with?
next prev parent reply other threads:[~2021-07-27 21:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 0:12 [PATCH v4] mm: Enable suspend-only swap spaces Evan Green
2021-07-27 9:48 ` David Hildenbrand
2021-07-27 12:21 ` David Hildenbrand
2021-07-27 16:31 ` Evan Green
2021-07-27 21:18 ` Andrew Morton [this message]
2021-08-03 18:00 ` Evan Green
2021-08-17 18:32 ` Pavel Machek
2021-07-30 13:15 ` Karel Zak
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