Commits on Feb 27, 2019

1. Fix most zfs_arc_* mod params not actually being modifiable at runtime …

   Most of the zfs_arc_* module parameters do not have their values used by
   the ARC code directly. Instead, there is a function, arc_tuning_update,
   which is called during module initialization and periodically
   thereafter, whose job is to fetch the module parameter values, clamp/
   limit them appropriately, and then assign those values to a separate set
   of internal variables that are actually referenced by the ARC code.
   
   Commit 3ec34e5 featured an overhaul of arc_reclaim_thread, which is the
   former location where the post-init-time calls to arc_tuning_update
   would occur. The rework split the work previously done by the
   arc_reclaim_thread into a pair of replacement threads; and
   unfortunately, the call to arc_tuning_update fell through the cracks and
   was lost in the reorganization.
   
   This meant that changing almost any ARC-related zfs module parameter via
   /sys/module/zfs/parameters/ would result in the module parameter value
   itself appearing to change; however the modification would not actually
   propagate to the ARC code and have any real effect.
   
   This commit reinstates the post-init-time call to arc_tuning_update. It
   is now called during arc_adjust_cb_check; this should be equivalent to
   its former call location in arc_reclaim_thread.
   
   Signed-off-by: Justin Gottula <justin@jgottula.com>

   

   jgottula committed Feb 27, 2019
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