MFV r336930: 9284 arc_reclaim_thread has 2 jobs
arc_reclaim_thread() calls arc_adjust() after calling
arc_kmem_reap_now(); arc_adjust() signals arc_get_data_buf() to
indicate that we may no longer be arc_is_overflowing().
The problem is, arc_kmem_reap_now() can take several seconds to
complete, has no impact on arc_is_overflowing(), but due to how the
code is structured, can impact how long the ARC will remain in the
arc_is_overflowing() state.
The fix is to use seperate threads to:
- keep arc_size under arc_c, by calling arc_adjust(), which improves arc_is_overflowing()
- keep enough free memory in the system, by calling arc_kmem_reap_now() plus arc_shrink(), which improves arc_available_memory().
illumos/illumos-gate@de753e34f9c399037936e8bc547d823bba9d4b0d
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Tim Kordas <tim.kordas@joyent.com>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Brad Lewis <brad.lewis@delphix.com>