mirror_zfs/module
George Wilson 7a61440761 Illumos #3552
3552 condensing one space map burns 3 seconds of CPU in spa_sync()
     thread (fix race condition)

References:
  https://www.illumos.org/issues/3552
  illumos/illumos-gate@03f8c36688

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

Porting notes:

This fixes an upstream regression that was introduced in commit
zfsonlinux/zfs@e51be06697, which
ported the Illumos 3552 changes. This fix was added to upstream
rather quickly, but at the time of the port, no one spotted it and
the race was rare enough that it passed our regression tests. I
discovered this when comparing our metaslab.c to the illumos
metaslab.c.

Without this change it is possible for metaslab_group_alloc() to
consume a large amount of cpu time.  Since this occurs under a
mutex in a rcu critical section the kernel will log this to the
console as a self-detected cpu stall as follows:

  INFO: rcu_sched self-detected stall on CPU { 0}
  (t=60000 jiffies g=11431890 c=11431889 q=18271)

Closes #1687
Closes #1720
Closes #1731
Closes #1747
2013-10-18 14:34:01 -07:00
..
avl Add script for builtin module building. 2012-07-26 13:45:09 -07:00
nvpair Illumos #3464 2013-09-04 16:01:24 -07:00
unicode Add script for builtin module building. 2012-07-26 13:45:09 -07:00
zcommon Illumos #2882, #2883, #2900 2013-09-04 15:49:00 -07:00
zfs Illumos #3552 2013-10-18 14:34:01 -07:00
zpios Illumos #3464 2013-09-04 16:01:24 -07:00
.gitignore gitignore: anchor entries at their respective directory 2013-04-02 10:50:17 -07:00
Makefile.in Add KMODDIR to install target 2013-03-06 15:46:40 -08:00