From: Matthew Wilcox <willy@infradead.org>
To: Hannes Reinecke <hare@suse.de>
Cc: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>,
david@fromorbit.com, djwong@kernel.org, hch@lst.de,
Keith Busch <kbusch@kernel.org>,
mcgrof@kernel.org, akpm@linux-foundation.org, brauner@kernel.org,
chandan.babu@oracle.com, gost.dev@samsung.com,
john.g.garry@oracle.com, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-xfs@vger.kernel.org, p.raghav@samsung.com,
ritesh.list@gmail.com, ziy@nvidia.com
Subject: Re: [RFC] iomap: use huge zero folio in iomap_dio_zero
Date: Fri, 17 May 2024 14:30:42 +0100 [thread overview]
Message-ID: <ZkdcAsENj2mBHh91@casper.infradead.org> (raw)
In-Reply-To: <ef22fc06-0227-419c-8f25-38aff7f5e3eb@suse.de>
On Fri, May 17, 2024 at 02:36:29PM +0200, Hannes Reinecke wrote:
> > +#define ZERO_FSB_SIZE (65536)
> > +#define ZERO_FSB_ORDER (get_order(ZERO_FSB_SIZE))
> > +extern struct page *zero_fs_block;
> > +
> > /*
> > * char_dev.c
> > */
> But why?
> We already have a perfectly fine hugepage zero page in huge_memory.c.
> Shouldn't we rather export that one and use it?
> (Actually I have some patches for doing so...)
But we don't necessarily. We only have it if
do_huge_pmd_anonymous_page() satisfies:
if (!(vmf->flags & FAULT_FLAG_WRITE) &&
!mm_forbids_zeropage(vma->vm_mm) &&
transparent_hugepage_use_zero_page()) {
ie we've taken a page fault on a PMD hole in a VMA, that VMA permits
PMD mappings to exist, the page fault was for read, the
forbids-huge-zeropage isn't set for this vma, and using the hugetlb zero
page isn't forbidden.
I'd like to see stats for how much the PMD-zero-page is actually used,
because I suspect it's not really used very much.
next prev parent reply other threads:[~2024-05-17 13:30 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-03 9:53 [PATCH v5 00/11] enable bs > ps in XFS Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 01/11] readahead: rework loop in page_cache_ra_unbounded() Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 02/11] fs: Allow fine-grained control of folio sizes Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 03/11] filemap: allocate mapping_min_order folios in the page cache Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 04/11] readahead: allocate folios with mapping_min_order in readahead Luis Chamberlain
2024-05-03 14:32 ` Hannes Reinecke
2024-05-03 9:53 ` [PATCH v5 05/11] mm: split a folio in minimum folio order chunks Luis Chamberlain
2024-05-03 14:53 ` Zi Yan
2024-05-15 15:32 ` Matthew Wilcox
2024-05-16 14:56 ` Pankaj Raghav (Samsung)
2024-05-03 9:53 ` [PATCH v5 06/11] filemap: cap PTE range to be created to allowed zero fill in folio_map_range() Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Luis Chamberlain
2024-05-07 14:58 ` [RFC] iomap: use huge zero folio in iomap_dio_zero Pankaj Raghav (Samsung)
2024-05-07 15:11 ` Zi Yan
2024-05-07 16:11 ` Christoph Hellwig
2024-05-08 11:39 ` Pankaj Raghav (Samsung)
2024-05-08 11:43 ` Christoph Hellwig
2024-05-09 12:31 ` Pankaj Raghav (Samsung)
2024-05-09 12:46 ` Christoph Hellwig
2024-05-09 12:55 ` Pankaj Raghav (Samsung)
2024-05-09 12:58 ` Christoph Hellwig
2024-05-09 14:32 ` Darrick J. Wong
2024-05-09 15:05 ` Christoph Hellwig
2024-05-09 15:08 ` Darrick J. Wong
2024-05-09 15:09 ` Christoph Hellwig
2024-05-15 0:50 ` Matthew Wilcox
2024-05-15 2:34 ` Keith Busch
2024-05-15 4:04 ` Matthew Wilcox
2024-05-15 15:59 ` Pankaj Raghav (Samsung)
2024-05-15 18:03 ` Matthew Wilcox
2024-05-16 15:02 ` Pankaj Raghav (Samsung)
2024-05-17 12:36 ` Hannes Reinecke
2024-05-17 12:56 ` Hannes Reinecke
2024-05-17 13:30 ` Matthew Wilcox [this message]
2024-05-15 11:48 ` Christoph Hellwig
2024-05-07 16:00 ` [PATCH v5 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Matthew Wilcox
2024-05-07 16:10 ` Christoph Hellwig
2024-05-07 16:11 ` Matthew Wilcox
2024-05-07 16:13 ` Christoph Hellwig
2024-05-08 4:24 ` Matthew Wilcox
2024-05-08 11:22 ` Pankaj Raghav (Samsung)
2024-05-08 11:36 ` Christoph Hellwig
2024-05-08 11:20 ` Pankaj Raghav (Samsung)
2024-05-03 9:53 ` [PATCH v5 08/11] xfs: use kvmalloc for xattr buffers Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 09/11] xfs: expose block size in stat Luis Chamberlain
2024-05-03 9:53 ` [PATCH v5 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count() Luis Chamberlain
2024-05-07 8:40 ` John Garry
2024-05-07 21:13 ` Darrick J. Wong
2024-05-08 11:28 ` Pankaj Raghav (Samsung)
2024-05-03 9:53 ` [PATCH v5 11/11] xfs: enable block size larger than page size support Luis Chamberlain
2024-05-07 0:05 ` Dave Chinner
-- strict thread matches above, loose matches on Subject: below --
2024-05-07 18:38 [RFC] iomap: use huge zero folio in iomap_dio_zero Ritesh Harjani
2024-05-08 11:42 ` Christoph Hellwig
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