writeback: add dirty_throttle_control->pos_ratio
wb_position_ratio() is used to calculate pos_ratio, which is used for two purposes. wb_update_dirty_ratelimit() uses it to adjust wb->[balanced_]dirty_ratelimit gradually and balance_dirty_pages() to immediately adjust dirty_ratelimit right before applying it to determine pause duration. While wb_update_dirty_ratelimit() is separately rate limited from balance_dirty_pages(), on the run where the ratelimit is updated, we end up calculating pos_ratio twice with the same parameters. This patch adds dirty_throttle_control->pos_ratio. balance_dirty_pages() calculates it once per run and wb_update_dirty_ratelimit() uses the value stored in dirty_throttle_control. This removes the duplicate calculation and also will help implementing memcg wb_domain. Signed-off-by:Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by:
Jens Axboe <axboe@fb.com>
parent
b1cbc6d4
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