From: Vlastimil Babka <vbabka@suse.cz>
To: Matthew Wilcox <willy@infradead.org>,
Johannes Weiner <hannes@cmpxchg.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] Memory folios for v5.15
Date: Tue, 31 Aug 2021 19:40:36 +0200 [thread overview]
Message-ID: <eef914fb-c3c4-effa-5bd8-81ee2495a2f9@suse.cz> (raw)
In-Reply-To: <YS1PzKLr2AWenbHF@casper.infradead.org>
On 8/30/21 23:38, Matthew Wilcox wrote:
> I think something that might actually help is if we added a pair of new
> GFP flags, __GFP_FAST and __GFP_DENSE. Dense allocations are those which
> are expected to live for a long time, and so the page allocator should
> try to group them with other dense allocations. Slab and page tables
> should use DENSE, along with things like superblocks, or fs bitmaps where
> the speed of allocation is almost unimportant, but attempting to keep
> them out of the way of other allocations is useful. Fast allocations
> are for allocations which should not live for very long. The speed of
> allocation dominates, and it's OK if the allocation gets in the way of
> defragmentation for a while.
Note we used to have GFP_TEMPORARY, but it didn't really work out:
https://lwn.net/Articles/732107/
> An example of another allocator that could care about DENSE vs FAST
> would be vmalloc. Today, it does:
>
> if (array_size > PAGE_SIZE) {
> area->pages = __vmalloc_node(array_size, 1, nested_gfp, node,
> area->caller);
> } else {
> area->pages = kmalloc_node(array_size, nested_gfp, node);
> }
>
> That's actually pretty bad; if you have, say, a 768kB vmalloc space,
> you need a 12kB array. We currently allocate 16kB for the array, when we
> could use alloc_pages_exact() to free the 4kB we're never going to use.
> If this is GFP_DENSE, we know it's a long-lived allocation and we can
> let somebody else use the extra 4kB. If it's not, it's probably not
> worth bothering with.
>
next prev parent reply other threads:[~2021-08-31 17:40 UTC|newest]
Thread overview: 162+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-23 19:01 [GIT PULL] Memory folios for v5.15 Matthew Wilcox
2021-08-23 21:26 ` Johannes Weiner
2021-08-23 22:06 ` Linus Torvalds
2021-08-24 2:20 ` Matthew Wilcox
2021-08-24 13:04 ` Matthew Wilcox
2021-08-23 22:15 ` Matthew Wilcox
2021-08-24 18:32 ` Johannes Weiner
2021-08-24 18:59 ` Linus Torvalds
2021-08-25 6:39 ` Christoph Hellwig
2021-08-24 19:44 ` Matthew Wilcox
2021-08-25 15:13 ` Johannes Weiner
2021-08-26 0:45 ` Darrick J. Wong
2021-08-27 14:07 ` Johannes Weiner
2021-08-27 18:44 ` Matthew Wilcox
2021-08-27 21:41 ` Dan Williams
2021-08-27 21:49 ` Matthew Wilcox
2021-08-30 17:32 ` Johannes Weiner
2021-08-30 18:22 ` Matthew Wilcox
2021-08-30 20:27 ` Johannes Weiner
2021-08-30 21:38 ` Matthew Wilcox
2021-08-31 17:40 ` Vlastimil Babka [this message]
2021-09-01 17:43 ` Johannes Weiner
2021-09-02 15:13 ` Zi Yan
2021-09-06 14:00 ` Vlastimil Babka
2021-08-31 18:50 ` Eric W. Biederman
2021-08-26 8:58 ` David Howells
2021-08-27 10:03 ` Johannes Weiner
2021-08-27 12:05 ` Matthew Wilcox
2021-08-27 10:49 ` David Howells
2021-08-24 15:54 ` David Howells
2021-08-24 17:56 ` Matthew Wilcox
2021-08-24 18:26 ` Linus Torvalds
2021-08-24 18:29 ` Linus Torvalds
2021-08-24 19:26 ` Theodore Ts'o
2021-08-24 19:34 ` David Howells
2021-08-24 20:02 ` Theodore Ts'o
2021-08-24 21:32 ` David Howells
2021-08-25 12:08 ` Jeff Layton
2021-08-24 19:01 ` Matthew Wilcox
2021-08-24 19:11 ` Linus Torvalds
2021-08-24 19:23 ` Matthew Wilcox
2021-08-24 19:44 ` Theodore Ts'o
2021-08-24 20:00 ` Matthew Wilcox
2021-08-25 6:32 ` Christoph Hellwig
2021-08-25 9:01 ` Rasmus Villemoes
2021-08-26 6:32 ` Amir Goldstein
2021-08-25 12:03 ` Jeff Layton
2021-08-26 0:59 ` Darrick J. Wong
2021-08-26 4:02 ` Nicholas Piggin
2021-09-01 12:58 ` Mike Rapoport
2021-08-24 19:35 ` David Howells
2021-08-24 20:35 ` Vlastimil Babka
2021-08-24 20:40 ` Vlastimil Babka
2021-08-24 19:11 ` David Howells
2021-08-24 19:25 ` Linus Torvalds
2021-08-24 19:38 ` Linus Torvalds
2021-08-24 19:48 ` Linus Torvalds
2021-08-26 17:18 ` Matthew Wilcox
2021-08-24 19:59 ` David Howells
2021-10-05 13:52 ` Matthew Wilcox
2021-10-05 17:29 ` Johannes Weiner
2021-10-05 17:32 ` David Hildenbrand
2021-10-05 18:30 ` Matthew Wilcox
2021-10-05 19:56 ` Jason Gunthorpe
2021-08-28 3:29 ` Matthew Wilcox
2021-09-09 12:43 ` Christoph Hellwig
2021-09-09 13:56 ` Vlastimil Babka
2021-09-09 18:16 ` Johannes Weiner
2021-09-09 18:44 ` Matthew Wilcox
2021-09-09 22:03 ` Johannes Weiner
2021-09-09 22:48 ` Matthew Wilcox
2021-09-09 19:17 ` John Hubbard
2021-09-09 19:23 ` Matthew Wilcox
2021-09-10 20:16 ` Folio discussion recap Kent Overstreet
2021-09-11 1:23 ` Kirill A. Shutemov
2021-09-13 11:32 ` Michal Hocko
2021-09-13 18:12 ` Johannes Weiner
2021-09-15 15:40 ` Johannes Weiner
2021-09-15 17:55 ` Damian Tometzki
2021-09-16 2:58 ` Darrick J. Wong
2021-09-16 16:54 ` Johannes Weiner
2021-09-17 5:24 ` Dave Chinner
2021-09-17 7:18 ` Christoph Hellwig
2021-09-17 16:31 ` Johannes Weiner
2021-09-17 20:57 ` Kirill A. Shutemov
2021-09-17 21:17 ` Kent Overstreet
2021-09-17 22:02 ` Kirill A. Shutemov
2021-09-17 22:21 ` Kent Overstreet
2021-09-17 23:15 ` Johannes Weiner
2021-09-20 10:03 ` Kirill A. Shutemov
2021-09-17 21:13 ` Kent Overstreet
2021-09-17 22:25 ` Theodore Ts'o
2021-09-17 23:35 ` Josef Bacik
2021-09-18 1:04 ` Dave Chinner
2021-09-18 4:51 ` Kent Overstreet
2021-09-20 1:04 ` Dave Chinner
2021-09-16 21:58 ` David Howells
2021-09-20 2:17 ` Matthew Wilcox
2021-09-21 19:47 ` Johannes Weiner
2021-09-21 20:38 ` Matthew Wilcox
2021-09-21 21:11 ` Kent Overstreet
2021-09-21 21:22 ` Folios for 5.15 request - Was: re: Folio discussion recap - Kent Overstreet
2021-09-22 15:08 ` Johannes Weiner
2021-09-22 15:46 ` Kent Overstreet
2021-09-22 16:26 ` Matthew Wilcox
2021-09-22 16:56 ` Chris Mason
2021-09-22 19:54 ` Matthew Wilcox
2021-09-22 20:15 ` Kent Overstreet
2021-09-22 20:21 ` Linus Torvalds
2021-09-23 5:42 ` Kent Overstreet
2021-09-23 18:00 ` Johannes Weiner
2021-09-23 19:31 ` Matthew Wilcox
2021-09-23 20:20 ` Kent Overstreet
2021-10-16 3:28 ` Matthew Wilcox
2021-10-18 16:47 ` Johannes Weiner
2021-10-18 18:12 ` Kent Overstreet
2021-10-18 20:45 ` Johannes Weiner
2021-10-19 16:11 ` Splitting struct page into multiple types " Kent Overstreet
2021-10-19 17:06 ` Gao Xiang
2021-10-19 17:34 ` Matthew Wilcox
2021-10-19 17:54 ` Gao Xiang
2021-10-20 17:46 ` Kent Overstreet
2021-10-19 17:37 ` Jason Gunthorpe
2021-10-19 21:14 ` David Howells
2021-10-18 18:28 ` Folios for 5.15 request " Matthew Wilcox
2021-10-18 21:56 ` Johannes Weiner
2021-10-18 23:16 ` Kirill A. Shutemov
2021-10-19 15:16 ` Johannes Weiner
2021-10-20 3:19 ` Matthew Wilcox
2021-10-20 7:50 ` David Hildenbrand
2021-10-20 17:26 ` Matthew Wilcox
2021-10-20 18:04 ` David Hildenbrand
2021-10-21 6:51 ` Christoph Hellwig
2021-10-21 7:21 ` David Hildenbrand
2021-10-21 12:03 ` Kent Overstreet
2021-10-21 12:35 ` David Hildenbrand
2021-10-21 12:38 ` Christoph Hellwig
2021-10-21 13:00 ` David Hildenbrand
2021-10-21 12:41 ` Matthew Wilcox
2021-10-20 17:39 ` Kent Overstreet
2021-10-21 21:37 ` Johannes Weiner
2021-10-22 1:52 ` Matthew Wilcox
2021-10-22 7:59 ` David Hildenbrand
2021-10-22 13:01 ` Matthew Wilcox
2021-10-22 14:40 ` David Hildenbrand
2021-10-23 2:22 ` Matthew Wilcox
2021-10-23 5:02 ` Christoph Hellwig
2021-10-23 9:58 ` David Hildenbrand
2021-10-23 16:00 ` Kent Overstreet
2021-10-23 21:41 ` Matthew Wilcox
2021-10-23 22:23 ` Kent Overstreet
2021-10-25 15:35 ` Johannes Weiner
2021-10-25 15:52 ` Matthew Wilcox
2021-10-25 16:05 ` Kent Overstreet
2021-10-16 19:07 ` Matthew Wilcox
2021-10-18 17:25 ` Johannes Weiner
2021-09-21 22:18 ` Folio discussion recap Matthew Wilcox
2021-09-23 0:45 ` Ira Weiny
2021-09-23 3:41 ` Matthew Wilcox
2021-09-23 22:12 ` Ira Weiny
2021-09-29 15:24 ` Matthew Wilcox
2021-09-21 21:59 ` Johannes Weiner
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