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From: Kent Overstreet <kent.overstreet@gmail.com>
To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	viro@zeniv.linux.org.uk, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Subject: [PATCH 0/2] generic_file_buffered_read() refactoring & optimization
Date: Tue,  9 Jun 2020 20:10:34 -0400	[thread overview]
Message-ID: <20200610001036.3904844-1-kent.overstreet@gmail.com> (raw)

This is a small patch series that's been in the bcachefs tree for awhile.

In the buffered read path, we look up a page in the page cache, then copy from
that page in a loop - i.e. mixing the data copies in between looking up each
individual page. When we're doing large reads from the page cache, this is some
pretty major overhead.

This just reworks generic_file_buffered_read() to use find_get_pages_contig()
and work on an array of pages. It's a pretty significant performance
improvement for large buffered reads, and doesn't regress performance on single
page reads.

As a bonus, generic_file_buffered_read() gets broken up into multiple functions
that are _somewhat_ easier to follow.

Kent Overstreet (2):
  fs: Break generic_file_buffered_read up into multiple functions
  fs: generic_file_buffered_read() now uses find_get_pages_contig

 mm/filemap.c | 486 +++++++++++++++++++++++++++++----------------------
 1 file changed, 273 insertions(+), 213 deletions(-)

-- 
2.27.0


             reply	other threads:[~2020-06-10  0:11 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-10  0:10 Kent Overstreet [this message]
2020-06-10  0:10 ` [PATCH 1/2] fs: Break generic_file_buffered_read up into multiple functions Kent Overstreet
2020-06-10  0:10 ` [PATCH 2/2] fs: generic_file_buffered_read() now uses find_get_pages_contig Kent Overstreet
2020-06-10  0:47   ` Matthew Wilcox
2020-06-10  1:08     ` Kent Overstreet
2020-06-10  1:38   ` Matthew Wilcox
2020-06-10  1:46     ` Kent Overstreet
2020-06-10  1:36 ` [PATCH v2 1/2] fs: Break generic_file_buffered_read up into multiple functions Kent Overstreet
2020-06-10  1:36 ` [PATCH v2 2/2] fs: generic_file_buffered_read() now uses find_get_pages_contig Kent Overstreet
2020-06-18  1:05   ` Andrew Morton
2020-06-19  3:20     ` [PATCH v3 0/2] generic_file_buffered_read() refactoring & optimization Kent Overstreet
2020-06-19 12:59       ` Christoph Hellwig
2020-06-19 18:44         ` Kent Overstreet
2020-06-19  3:20     ` [PATCH v3 1/2] fs: Break generic_file_buffered_read up into multiple functions Kent Overstreet
2020-06-19  3:20     ` [PATCH v3 2/2] fs: generic_file_buffered_read() now uses find_get_pages_contig Kent Overstreet
2020-06-30  0:12 ` Fixup patch for [PATCH 0/2] generic_file_buffered_read() refactoring & optimization Kent Overstreet

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