Linux-Fsdevel Archive on lore.kernel.org
 help / color / Atom feed
From: NeilBrown <neilb@suse.com>
To: Jeff Layton <jlayton@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
	Martin Wilck <mwilck@suse.de>,
	linux-fsdevel@vger.kernel.org,
	Frank Filz <ffilzlnx@mindspring.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 00/12] Series short description
Date: Mon, 05 Nov 2018 12:30:47 +1100
Message-ID: <154138128401.31651.1381177427603557514.stgit@noble> (raw)

Here is the respin on this series with the file_lock properly
initlized for unlock requests.
I found one that I had missed before - in locks_remove_flock()
The change makes this code smaller!

Original series description:

If you have a many-core machine, and have many threads all wanting to
briefly lock a give file (udev is known to do this), you can get quite
poor performance.

When one thread releases a lock, it wakes up all other threads that
are waiting (classic thundering-herd) - one will get the lock and the
others go to sleep.
When you have few cores, this is not very noticeable: by the time the
4th or 5th thread gets enough CPU time to try to claim the lock, the
earlier threads have claimed it, done what was needed, and released.
With 50+ cores, the contention can easily be measured.

This patchset creates a tree of pending lock request in which siblings
don't conflict and each lock request does conflict with its parent.
When a lock is released, only requests which don't conflict with each
other a woken.

Testing shows that lock-acquisitions-per-second is now fairly stable even
as number of contending process goes to 1000.  Without this patch,
locks-per-second drops off steeply after a few 10s of processes.

There is a small cost to this extra complexity.
At 20 processes running a particular test on 72 cores, the lock
acquisitions per second drops from 1.8 million to 1.4 million with
this patch.  For 100 processes, this patch still provides 1.4 million
while without this patch there are about 700,000.

NeilBrown


---

NeilBrown (12):
      fs/locks: rename some lists and pointers.
      fs/locks: split out __locks_wake_up_blocks().
      NFS: use locks_copy_lock() to copy locks.
      gfs2: properly initial file_lock used for unlock.
      ocfs2: properly initial file_lock used for unlock.
      locks: use properly initialized file_lock when unlocking.
      fs/locks: allow a lock request to block other requests.
      fs/locks: always delete_block after waiting.
      fs/locks: change all *_conflict() functions to return bool.
      fs/locks: create a tree of dependent requests.
      locks: merge posix_unblock_lock() and locks_delete_block()
      VFS: locks: remove unnecessary white space.


 fs/cifs/file.c                  |    4 -
 fs/gfs2/file.c                  |   10 +-
 fs/lockd/svclock.c              |    2 
 fs/locks.c                      |  253 +++++++++++++++++++++------------------
 fs/nfs/nfs4proc.c               |    6 +
 fs/nfsd/nfs4state.c             |    6 -
 fs/ocfs2/locks.c                |   10 +-
 include/linux/fs.h              |   11 +-
 include/trace/events/filelock.h |   16 +-
 9 files changed, 173 insertions(+), 145 deletions(-)

--
Signature

             reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-05  1:30 NeilBrown [this message]
2018-11-05  1:30 ` [PATCH 02/12] fs/locks: split out __locks_wake_up_blocks() NeilBrown
2018-11-05  1:30 ` [PATCH 08/12] fs/locks: always delete_block after waiting NeilBrown
2018-11-05  1:30 ` [PATCH 06/12] locks: use properly initialized file_lock when unlocking NeilBrown
2018-11-05  1:30 ` [PATCH 01/12] fs/locks: rename some lists and pointers NeilBrown
2018-11-08 20:26   ` J. Bruce Fields
2018-11-09  0:32     ` NeilBrown
2018-11-09  3:11       ` J. Bruce Fields
2018-11-05  1:30 ` [PATCH 04/12] gfs2: properly initial file_lock used for unlock NeilBrown
2018-11-05 12:18   ` Jeff Layton
2018-11-06  1:48     ` NeilBrown
2018-11-06 13:20       ` Jeff Layton
2018-11-05  1:30 ` [PATCH 05/12] ocfs2: " NeilBrown
2018-11-05  1:30 ` [PATCH 07/12] fs/locks: allow a lock request to block other requests NeilBrown
2018-11-05  1:30 ` [PATCH 09/12] fs/locks: change all *_conflict() functions to return bool NeilBrown
2018-11-05  1:30 ` [PATCH 03/12] NFS: use locks_copy_lock() to copy locks NeilBrown
2018-11-05  1:30 ` [PATCH 11/12] locks: merge posix_unblock_lock() and locks_delete_block() NeilBrown
2018-11-05  1:30 ` [PATCH 10/12] fs/locks: create a tree of dependent requests NeilBrown
2018-11-08 21:30   ` J. Bruce Fields
2018-11-09  0:38     ` NeilBrown
2018-11-09  3:09       ` J. Bruce Fields
2018-11-09  6:24         ` NeilBrown
2018-11-09 15:08           ` J. Bruce Fields
2018-11-05  1:30 ` [PATCH 12/12] VFS: locks: remove unnecessary white space NeilBrown
2018-11-08 21:35 ` [PATCH 00/12] Series short description J. Bruce Fields

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=154138128401.31651.1381177427603557514.stgit@noble \
    --to=neilb@suse.com \
    --cc=bfields@fieldses.org \
    --cc=ffilzlnx@mindspring.com \
    --cc=jlayton@kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mwilck@suse.de \
    --cc=viro@zeniv.linux.org.uk \
    /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

Linux-Fsdevel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-fsdevel/0 linux-fsdevel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-fsdevel linux-fsdevel/ https://lore.kernel.org/linux-fsdevel \
		linux-fsdevel@vger.kernel.org
	public-inbox-index linux-fsdevel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-fsdevel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git