From: Michal Hocko <mhocko@kernel.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@suse.de>,
David Hildenbrand <david@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Vlastimil Babka <vbabka@suse.cz>, Zi Yan <ziy@nvidia.com>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Minchan Kim <minchan@kernel.org>, Hugh Dickins <hughd@google.com>,
Alexander Duyck <alexander.duyck@gmail.com>
Subject: Re: [RFC 0/3] mm: Discard lazily freed pages when migrating
Date: Wed, 4 Mar 2020 12:26:53 +0100 [thread overview]
Message-ID: <20200304112653.GH16139@dhcp22.suse.cz> (raw)
In-Reply-To: <87blpc2wxj.fsf@yhuang-dev.intel.com>
On Wed 04-03-20 19:15:20, Huang, Ying wrote:
> Michal Hocko <mhocko@kernel.org> writes:
>
> > On Tue 03-03-20 19:49:53, Huang, Ying wrote:
[...]
> >> Because the penalty difference is so large, I
> >> think it may be a good idea to always put clean MADV_FREE pages at the
> >> tail of the inactive file LRU list?
> >
> > You are again making assumptions without giving any actual real
> > examples. Reconstructing MADV_FREE pages cost can differ a lot.
>
> In which situation the cost to reconstruct MADV_FREE pages can be higher
> than the cost to allocate file cache page and read from disk? Heavy
> contention on mmap_sem?
Allocating a page might be really costly but even without that.
Reconstructnig the content of the page can be really high and actually
much larger than an IO to get a page from the storage. Consider
decompression or some other transformations to get the content.
Userspace has means to detect that the content is still up-to-date as
already has been mentioned so all those steps can be avoided.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-03-04 11:26 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 3:38 [RFC 0/3] mm: Discard lazily freed pages when migrating Huang, Ying
2020-02-28 3:38 ` [RFC 1/3] mm, migrate: Check return value of try_to_unmap() Huang, Ying
2020-02-28 3:38 ` [RFC 2/3] mm: Add a new page flag PageLayzyFree() for MADV_FREE Huang, Ying
2020-02-28 6:13 ` David Hildenbrand
2020-02-28 6:47 ` Huang, Ying
2020-02-28 6:47 ` Huang, Ying
2020-03-15 8:18 ` Wei Yang
2020-03-15 8:54 ` Mika Penttilä
2020-03-15 12:22 ` Wei Yang
2020-03-16 1:21 ` Huang, Ying
2020-03-16 1:21 ` Huang, Ying
2020-03-16 22:38 ` Wei Yang
2020-02-28 3:38 ` [RFC 3/3] mm: Discard lazily freed pages when migrating Huang, Ying
2020-02-28 3:42 ` [RFC 0/3] " Matthew Wilcox
2020-02-28 7:25 ` Huang, Ying
2020-02-28 7:25 ` Huang, Ying
2020-02-28 8:22 ` David Hildenbrand
2020-02-28 8:55 ` Huang, Ying
2020-02-28 8:55 ` Huang, Ying
2020-02-28 9:49 ` Mel Gorman
2020-03-02 11:23 ` Huang, Ying
2020-03-02 11:23 ` Huang, Ying
2020-03-02 15:16 ` Mel Gorman
2020-03-03 1:51 ` Huang, Ying
2020-03-03 1:51 ` Huang, Ying
2020-03-03 8:09 ` Michal Hocko
2020-03-03 8:47 ` Huang, Ying
2020-03-03 8:47 ` Huang, Ying
2020-03-03 8:58 ` Michal Hocko
2020-03-03 11:49 ` Huang, Ying
2020-03-03 11:49 ` Huang, Ying
2020-03-04 9:58 ` Michal Hocko
2020-03-04 10:56 ` Mel Gorman
2020-03-05 1:42 ` Huang, Ying
2020-03-05 1:42 ` Huang, Ying
2020-03-04 11:15 ` Huang, Ying
2020-03-04 11:15 ` Huang, Ying
2020-03-04 11:26 ` Michal Hocko [this message]
2020-03-05 1:45 ` Huang, Ying
2020-03-05 1:45 ` Huang, Ying
2020-03-05 10:48 ` Mel Gorman
2020-03-06 4:05 ` Huang, Ying
2020-03-06 4:05 ` Huang, Ying
2020-03-09 5:26 ` Huang, Ying
2020-03-09 5:26 ` Huang, Ying
2020-03-03 13:02 ` Mel Gorman
2020-03-04 0:33 ` Huang, Ying
2020-03-04 0:33 ` Huang, Ying
2020-02-28 9:50 ` Michal Hocko
2020-02-28 10:15 ` Michal Hocko
2020-02-28 13:45 ` Johannes Weiner
2020-03-02 14:12 ` Huang, Ying
2020-03-02 14:12 ` Huang, Ying
2020-03-02 14:23 ` David Hildenbrand
2020-03-03 0:25 ` Huang, Ying
2020-03-03 0:25 ` Huang, Ying
2020-03-02 14:25 ` Michal Hocko
2020-03-03 1:30 ` Huang, Ying
2020-03-03 1:30 ` Huang, Ying
2020-03-03 8:19 ` Michal Hocko
2020-03-03 11:36 ` Huang, Ying
2020-03-03 11:36 ` Huang, Ying
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