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Tue, 09 Jun 2020 17:10:40 -0700 (PDT) From: Kent Overstreet 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 Subject: [PATCH 0/2] generic_file_buffered_read() refactoring & optimization Date: Tue, 9 Jun 2020 20:10:34 -0400 Message-Id: <20200610001036.3904844-1-kent.overstreet@gmail.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-Rspamd-Queue-Id: 930FE6C3A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.031221, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 e= ach individual page. When we're doing large reads from the page cache, this i= s some pretty major overhead. This just reworks generic_file_buffered_read() to use find_get_pages_cont= ig() 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 fun= ctions 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(-) --=20 2.27.0