linux-kernel - [PATCH 0/9 v3] locks: avoid thundering-herd wake-ups

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Date:   Wed, 24 Oct 2018 09:43:54 +1100
From:   NeilBrown <neilb@...e.com>
To:     Jeff Layton <jlayton@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     "J. Bruce Fields" <bfields@...ldses.org>,
        Martin Wilck <mwilck@...e.de>, linux-fsdevel@...r.kernel.org,
        Frank Filz <ffilzlnx@...dspring.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 0/9 v3] locks: avoid thundering-herd wake-ups

This took longer that I had wanted, due to various reasons - sorry.
And I'm now posting it in a merge window, which is not ideal.  I don't
expect it to be included in this merge window and I won't be at all
impatient for review, but I didn't want to delay it further.

Testing found some problems, particularly the need to use
locks_copy_lock in NFS.  And there was a small thinko in there that
effectively removed all the speed gains :-(

But this version:
 - shows excellent scalability with lots of threads on lots of CPUs
   contending on a single file
 - avoids the problems that Bruce found
 - seems to work.

Thanks,
NeilBrown


---

NeilBrown (9):
      fs/locks: rename some lists and pointers.
      fs/locks: split out __locks_wake_up_blocks().
      NFS: use locks_copy_lock() to copy locks.
      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/lockd/svclock.c              |    2 
 fs/locks.c                      |  231 ++++++++++++++++++++++-----------------
 fs/nfs/nfs4proc.c               |    6 +
 fs/nfsd/nfs4state.c             |    6 +
 include/linux/fs.h              |   11 +-
 include/trace/events/filelock.h |   16 +--
 7 files changed, 153 insertions(+), 123 deletions(-)

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