git: hammer2 - Limit bulkfree cpu and SSD I/O

Matthew Dillon dillon at
Mon Sep 11 14:52:27 PDT 2017

commit 4ff0b4082e606911e580e65ca217fc1145c86d14
Author: Matthew Dillon <dillon at>
Date:   Mon Sep 11 14:46:31 2017 -0700

    hammer2 - Limit bulkfree cpu and SSD I/O
    * Limit resource utilization when running bulkfree.  The default is 5000
      tps (meta-data blocks per second) and can be changed via the
      vfs.hammer2.bulkfree_tps sysctl.
    * Designed primarily to limit cpu utilization when meta-data is cached,
      and to limit SSD utilization otherwise.  This feature generally cannot
      be used to limit HDD utilization because it cannot currently distinguish
      between cached and uncached I/O.  Setting a low a number to accomodate
      a HDD will cause bulkfree to take way too long to run.

Summary of changes:
 sbin/hammer2/hammer2.8             | 10 ++++++++--
 sys/vfs/hammer2/hammer2.h          |  1 +
 sys/vfs/hammer2/hammer2_bulkfree.c | 32 +++++++++++++++++++++++++++++++-
 sys/vfs/hammer2/hammer2_subr.c     |  2 ++
 sys/vfs/hammer2/hammer2_vfsops.c   |  3 +++
 5 files changed, 45 insertions(+), 3 deletions(-)

DragonFly BSD source repository

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