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git: HAMMER VFS - The backend flusher now sorts inodes

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 2 Nov 2009 09:20:49 -0800 (PST)

commit ff003b11ff22dd10f420eba8a38b7c0838d79acd
Author: Matthew Dillon <dillon@apollo.backplane.com>
Date:   Mon Nov 2 09:11:46 2009 -0800

    HAMMER VFS - The backend flusher now sorts inodes
    * Change the tailq of inodes in a flush group to a red-black tree.
      The flusher now processes inodes in sorted order and breaks them up
      into larger sets for concurrent flushing.  The flusher threads are thus
      more likely to concurrently process inodes which are fairly far apart
      in the B-Tree.
      This greatly reduces lock interference between flusher threads.  However,
      B-Tree deadlocks are still an issue between inodes undergoing flushes
      and front-end access operations.  This can be observed by noting periods
      of low dev-write activity in 'hammer iostats 1' output during a blogbench
      test.  The hammer-S* kernel threads will likely be in a 'hmrdlk' state
      at the same time.
    * Add sysctl vfs.hammer.limit_reclaim to set the maximum
      number of inodes with no vnode associations, default 4000.
      NOTE: For debugging only, setting this value too high will blow
      out the kmalloc pool.

Summary of changes:
 sys/vfs/hammer/hammer.h         |   17 ++++++++++-------
 sys/vfs/hammer/hammer_flusher.c |   23 +++++++++++++++++------
 sys/vfs/hammer/hammer_inode.c   |   16 ++++++++--------
 sys/vfs/hammer/hammer_vfsops.c  |    7 +++++--
 4 files changed, 40 insertions(+), 23 deletions(-)


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