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From: Al Viro <viro@zeniv.linux.org.uk>
To: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com,
	linux-afs@lists.infradead.org
Subject: Re: [PATCH v5 00/27] Memory Folios
Date: Thu, 1 Apr 2021 05:05:37 +0000	[thread overview]
Message-ID: <YGVUobKUMUtEy1PS@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <20210330210929.GR351017@casper.infradead.org>

On Tue, Mar 30, 2021 at 10:09:29PM +0100, Matthew Wilcox wrote:

> That's a very Intel-centric way of looking at it.  Other architectures
> support a multitude of page sizes, from the insane ia64 (4k, 8k, 16k, then
> every power of four up to 4GB) to more reasonable options like (4k, 32k,
> 256k, 2M, 16M, 128M).  But we (in software) shouldn't constrain ourselves
> to thinking in terms of what the hardware currently supports.  Google
> have data showing that for their workloads, 32kB is the goldilocks size.
> I'm sure for some workloads, it's much higher and for others it's lower.
> But for almost no workload is 4kB the right choice any more, and probably
> hasn't been since the late 90s.

Out of curiosity I looked at the distribution of file sizes in the
kernel tree:
71455 files total
0--4Kb		36702
4--8Kb		11820
8--16Kb		10066
16--32Kb	6984
32--64Kb	3804
64--128Kb	1498
128--256Kb	393
256--512Kb	108
512Kb--1Mb	35
1--2Mb		25
2--4Mb		5
4--6Mb		7
6--8Mb		4
12Mb		2 
14Mb		1
16Mb		1

... incidentally, everything bigger than 1.2Mb lives^Wshambles under
drivers/gpu/drm/amd/include/asic_reg/

Page size	Footprint
4Kb		1128Mb
8Kb		1324Mb
16Kb		1764Mb
32Kb		2739Mb
64Kb		4832Mb
128Kb		9191Mb
256Kb		18062Mb
512Kb		35883Mb
1Mb		71570Mb
2Mb		142958Mb

So for kernel builds (as well as grep over the tree, etc.) uniform 2Mb pages
would be... interesting.

  parent reply	other threads:[~2021-04-01  5:06 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-20  5:40 [PATCH v5 00/27] Memory Folios Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 01/27] fs/cachefiles: Remove wait_bit_key layout dependency Matthew Wilcox (Oracle)
2021-03-22  8:06   ` Christoph Hellwig
2021-03-20  5:40 ` [PATCH v5 02/27] mm/writeback: Add wait_on_page_writeback_killable Matthew Wilcox (Oracle)
2021-03-22  8:07   ` Christoph Hellwig
2021-03-20  5:40 ` [PATCH v5 03/27] afs: Use wait_on_page_writeback_killable Matthew Wilcox (Oracle)
2021-03-22  8:08   ` Christoph Hellwig
2021-03-20  5:40 ` [PATCH v5 04/27] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 05/27] mm: Add folio_pgdat and folio_zone Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 06/27] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 07/27] mm/debug: Add VM_BUG_ON_FOLIO and VM_WARN_ON_ONCE_FOLIO Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 08/27] mm: Add put_folio Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 09/27] mm: Add get_folio Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 10/27] mm: Create FolioFlags Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 11/27] mm: Handle per-folio private data Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 12/27] mm: Add folio_index, folio_file_page and folio_contains Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 13/27] mm/util: Add folio_mapping and folio_file_mapping Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 14/27] mm/memcg: Add folio wrappers for various functions Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 15/27] mm/filemap: Add unlock_folio Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 16/27] mm/filemap: Add lock_folio Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 17/27] mm/filemap: Add lock_folio_killable Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 18/27] mm/filemap: Add __lock_folio_async Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 19/27] mm/filemap: Add __lock_folio_or_retry Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 20/27] mm/filemap: Add wait_on_folio_locked Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 21/27] mm/filemap: Add end_folio_writeback Matthew Wilcox (Oracle)
2021-03-20  5:40 ` [PATCH v5 22/27] mm/writeback: Add wait_on_folio_writeback Matthew Wilcox (Oracle)
2021-03-20  5:41 ` [PATCH v5 23/27] mm/writeback: Add wait_for_stable_folio Matthew Wilcox (Oracle)
2021-03-20  5:41 ` [PATCH v5 24/27] mm/filemap: Convert wait_on_page_bit to wait_on_folio_bit Matthew Wilcox (Oracle)
2021-03-21  7:10   ` kernel test robot
2021-03-20  5:41 ` [PATCH v5 25/27] mm/filemap: Convert wake_up_page_bit to wake_up_folio_bit Matthew Wilcox (Oracle)
2021-03-20  5:41 ` [PATCH v5 26/27] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)
2021-03-20  7:54   ` kernel test robot
2021-03-20  5:41 ` [PATCH v5 27/27] mm/doc: Build kerneldoc for various mm files Matthew Wilcox (Oracle)
2021-03-22  3:25 ` [PATCH v5 00/27] Memory Folios Matthew Wilcox
2021-03-22  9:25 ` [PATCH v5 01/27] fs/cachefiles: Remove wait_bit_key layout dependency David Howells
2021-03-22  9:26 ` [PATCH v5 02/27] mm/writeback: Add wait_on_page_writeback_killable David Howells
2021-03-22  9:27 ` [PATCH v5 03/27] afs: Use wait_on_page_writeback_killable David Howells
2021-03-22 19:41   ` Matthew Wilcox
2021-03-22 17:59 ` [PATCH v5 00/27] Memory Folios Johannes Weiner
2021-03-22 18:47   ` Matthew Wilcox
2021-03-24  0:29     ` Johannes Weiner
2021-03-24  6:24       ` Matthew Wilcox
2021-03-26 17:48         ` Johannes Weiner
2021-03-29 16:58           ` Matthew Wilcox
2021-03-29 17:56             ` Matthew Wilcox
2021-03-30 19:30             ` Johannes Weiner
2021-03-30 21:09               ` Matthew Wilcox
2021-03-31 18:14                 ` Johannes Weiner
2021-03-31 18:28                   ` Matthew Wilcox
2021-04-01  5:05                 ` Al Viro [this message]
2021-04-01 12:07                   ` Matthew Wilcox
2021-04-01 16:00                   ` Johannes Weiner
2021-03-31 14:54               ` Christoph Hellwig
2021-03-23 15:50   ` Christoph Hellwig
2021-03-23 11:29 ` [PATCH v5 03/27] afs: Use wait_on_page_writeback_killable David Howells
2021-03-23 17:50 ` [PATCH v5 00/27] Memory Folios David Howells

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