linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: gregkh@linuxfoundation.org, lizefan@huawei.com, hannes@cmpxchg.org
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	kernel-team@fb.com
Subject: [PATCHSET] kernfs, cgroup: reimplement "cgroup.procs" reading for v2
Date: Tue, 20 Dec 2016 11:10:48 -0500	[thread overview]
Message-ID: <20161220161053.14994-1-tj@kernel.org> (raw)

On cgroup v1, the pid listings in "cgroup.procs" and "tasks" are
sorted which adds a lot of complications and overhead.  v2 doesn't
have such requirement and has been intentionally using a modified
sorting order so that the output doesn't look sorted to users.

This patchset re-implements "cgroup.procs" reading for v2 which simply
keeps a css_task_iter open while the file is being read.  Keeping the
iterator open makes it unnecessary to skip to the right position on
each read segment and associated errors - e.g. incorrectly skipping
over pids because earlier pids disappeared between the reads.

Using persistent iterator across multiple read calls requires
->release() callback to clean it up.  kernfs operations
->open/release() are added and piped through cftype.

This patchset contains the following five patches.

 0001-kernfs-make-kernfs_open_file-mmapped-a-bitfield.patch
 0002-kernfs-add-kernfs_ops-open-release-callbacks.patch
 0003-cgroup-add-cftype-open-release-callbacks.patch
 0004-cgroup-reimplement-reading-cgroup.procs-on-cgroup-v2.patch
 0005-cgroup-remove-cgroup_pid_fry-and-friends.patch

0001 is a misc kernfs patch and 0002 adds ->open/release() to kernfs.
0003 pipes ->open/release() through cftype.  0004 implements the new
cgroup.procs for v2 and 0005 removes the now unused sort order frying
logic.

Greg, would it be okay to route the kernfs patches through
cgroup/for-4.11?

The patches are also available in the following git branch.

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup2-procs

diffstat follows.  Thanks.

 fs/kernfs/dir.c             |    2 
 fs/kernfs/file.c            |   53 +++++++++++++++--
 fs/kernfs/kernfs-internal.h |    2 
 include/linux/cgroup-defs.h |    3 +
 include/linux/kernfs.h      |   12 +++-
 kernel/cgroup.c             |  130 +++++++++++++++++++++++++++++---------------
 6 files changed, 148 insertions(+), 54 deletions(-)

--
tejun

             reply	other threads:[~2016-12-20 16:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-20 16:10 Tejun Heo [this message]
2016-12-20 16:10 ` [PATCH 1/5] kernfs: make kernfs_open_file->mmapped a bitfield Tejun Heo
2016-12-20 16:17 ` [PATCHSET] kernfs, cgroup: reimplement "cgroup.procs" reading for v2 Tejun Heo
2016-12-20 16:12 Tejun Heo
2016-12-21  9:59 ` Greg KH
2016-12-26  6:22 ` Zefan Li
2016-12-27 19:53 ` Tejun Heo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20161220161053.14994-1-tj@kernel.org \
    --to=tj@kernel.org \
    --cc=cgroups@vger.kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=kernel-team@fb.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lizefan@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).