git: hammer2 - Add the vfs.hammer2.cluster_write sysctl back in

Matthew Dillon dillon at
Fri Aug 17 20:01:30 PDT 2018

commit f66cf3712cde69127a27daf2d8a805b7c7da52ce
Author: Matthew Dillon <dillon at>
Date:   Fri Aug 17 19:59:06 2018 -0700

    hammer2 - Add the vfs.hammer2.cluster_write sysctl back in
    * Value may be 0 or 1, defaults to 0 (disabled).  Was previously
    * By default H2 no longer sets B_CLUSTEROK on dirty buffers being
      written.  Theoretically this shouldn't be a problem because H2
      already uses a large 64KB buffer size.
    * Should improve I/O throughput on high-performance SSDs by removing
      kernel overhead and should also work better with vfsync's dirty
      buffer scan which is already sorted.

Summary of changes:
 sys/vfs/hammer2/hammer2.h        |  1 +
 sys/vfs/hammer2/hammer2_io.c     | 14 +++++++++-----
 sys/vfs/hammer2/hammer2_vfsops.c |  3 +++
 3 files changed, 13 insertions(+), 5 deletions(-)

DragonFly BSD source repository

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