linux-kernel - [PATCH 0/2] generic_file_buffered

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180815232632.32548-1-kent.overstreet@gmail.com>
Date:   Wed, 15 Aug 2018 19:26:30 -0400
From:   Kent Overstreet <kent.overstreet@...il.com>
To:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        viro@...iv.linux.org.uk
Cc:     Kent Overstreet <kent.overstreet@...il.com>
Subject: [PATCH 0/2] generic_file_buffered_read improvements

Small patch series to
 - firstly, refactor generic_file_buffered_read enough that it can be modified
   in more interesting ways without going insane, and then

 - secondly, change it to use find_get_pages_contig() to batch up the page
   operations, and then copy data to userspace in a separate loop that touches
   no other shared cachelines.

I've been seeing profiles where the radix tree lookups in the buffered read path
are a shockingly large portion of the profile (around 25%, if memory serves) -
that's what this patch series is addressing. I've benchmarked small block reads
as well, performance there is unaffected or slightly improved (it's within the
margin of error).

And as a bonus, the code that was all in generic_file_buffered_read() is now
_drastically_ easier to follow and modify. I haven't done as much refactoring as
I could have, I kept as much of the structure of the old code as I could just to
make things easier on myself, but I'm still pretty happy with the result.

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(-)

-- 
2.18.0