freebsd-dev/module
George Wilson 5853fe790d Illumos #3306, #3321
3306 zdb should be able to issue reads in parallel
3321 'zpool reopen' command should be documented in the man
     page and help

Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Matt Ahrens <matthew.ahrens@delphix.com>
Reviewed by: Christopher Siden <chris.siden@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  illumos/illumos-gate@31d7e8fa33
  https://www.illumos.org/issues/3306
  https://www.illumos.org/issues/3321

The vdev_file.c implementation in this patch diverges significantly
from the upstream version.  For consistenty with the vdev_disk.c
code the upstream version leverages the Illumos bio interfaces.
This makes sense for Illumos but not for ZoL for two reasons.

1) The vdev_disk.c code in ZoL has been rewritten to use the
   Linux block device interfaces which differ significantly
   from those in Illumos.  Therefore, updating the vdev_file.c
   to use the Illumos interfaces doesn't get you consistency
   with vdev_disk.c.

2) Using the upstream patch as is would requiring implementing
   compatibility code for those Solaris block device interfaces
   in user and kernel space.  That additional complexity could
   lead to confusion and doesn't buy us anything.

For these reasons I've opted to simply move the existing vn_rdwr()
as is in to the taskq function.  This has the advantage of being
low risk and easy to understand.  Moving the vn_rdwr() function
in to its own taskq thread also neatly avoids the possibility of
a stack overflow.

Finally, because of the additional work which is being handled by
the free taskq the number of threads has been increased.  The
thread count under Illumos defaults to 100 but was decreased to 2
in commit 08d08e due to contention.  We increase it to 8 until
the contention can be address by porting Illumos #3581.

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1354
2013-05-03 16:53:52 -07:00
..
avl Add script for builtin module building. 2012-07-26 13:45:09 -07:00
nvpair Illumos #2619 and #2747 2013-01-08 10:35:35 -08:00
unicode Add script for builtin module building. 2012-07-26 13:45:09 -07:00
zcommon Add snapdev=[hidden|visible] dataset property 2013-03-05 12:37:54 -08:00
zfs Illumos #3306, #3321 2013-05-03 16:53:52 -07:00
zpios Refresh links to web site 2013-03-06 15:46:41 -08:00
.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