Commit 0d960a38 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

writeback: clean up wb_dirty_limit() 



The function name wb_dirty_limit(), its argument @dirty and the local
variable @wb_dirty are mortally confusing given that the function
calculates per-wb threshold value not dirty pages, especially given
that @dirty and @wb_dirty are used elsewhere for dirty pages.

Let's rename the function to wb_calc_thresh() and wb_dirty to
wb_thresh.

Signed-off-by: default avatarTejun 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: default avatarJens Axboe <axboe@fb.com>
parent 733a572e

fs/fs-writeback.c

+1 −1
Original line number Diff line number Diff line
@@ -1081,7 +1081,7 @@ static bool over_bground_thresh(struct bdi_writeback *wb) 
	    global_page_state(NR_UNSTABLE_NFS) > background_thresh)

		return true;



	if (wb_stat(wb, WB_RECLAIMABLE) > wb_dirty_limit(wb, background_thresh))

	if (wb_stat(wb, WB_RECLAIMABLE) > wb_calc_thresh(wb, background_thresh))

		return true;



	return false;

include/linux/writeback.h

+1 −1
Original line number Diff line number Diff line
@@ -155,7 +155,7 @@ int dirty_writeback_centisecs_handler(struct ctl_table *, int, 
				      void __user *, size_t *, loff_t *);



void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);

unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty);

unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);



void __wb_update_bandwidth(struct bdi_writeback *wb,

			   unsigned long thresh,

mm/backing-dev.c

+3 −3
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) 
	struct bdi_writeback *wb = &bdi->wb;

	unsigned long background_thresh;

	unsigned long dirty_thresh;

	unsigned long bdi_thresh;

	unsigned long wb_thresh;

	unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;

	struct inode *inode;
@@ -67,7 +67,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) 
	spin_unlock(&wb->list_lock);



	global_dirty_limits(&background_thresh, &dirty_thresh);

	bdi_thresh = wb_dirty_limit(wb, dirty_thresh);

	wb_thresh = wb_calc_thresh(wb, dirty_thresh);



#define K(x) ((x) << (PAGE_SHIFT - 10))

	seq_printf(m,
@@ -87,7 +87,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) 
		   "state:              %10lx\n",

		   (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),

		   (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),

		   K(bdi_thresh),

		   K(wb_thresh),

		   K(dirty_thresh),

		   K(background_thresh),

		   (unsigned long) K(wb_stat(wb, WB_DIRTIED)),

mm/page-writeback.c

+15 −15
Original line number Diff line number Diff line
@@ -556,7 +556,7 @@ static unsigned long hard_dirty_limit(unsigned long thresh) 
}



/**

 * wb_dirty_limit - @wb's share of dirty throttling threshold

 * wb_calc_thresh - @wb's share of dirty throttling threshold

 * @wb: bdi_writeback to query

 * @dirty: global dirty limit in pages

 *
@@ -577,28 +577,28 @@ static unsigned long hard_dirty_limit(unsigned long thresh) 
 * The wb's share of dirty limit will be adapting to its throughput and

 * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.

 */

unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)

unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh)

{

	u64 wb_dirty;

	u64 wb_thresh;

	long numerator, denominator;

	unsigned long wb_min_ratio, wb_max_ratio;



	/*

	 * Calculate this BDI's share of the dirty ratio.

	 * Calculate this BDI's share of the thresh ratio.

	 */

	wb_writeout_fraction(wb, &numerator, &denominator);



	wb_dirty = (dirty * (100 - bdi_min_ratio)) / 100;

	wb_dirty *= numerator;

	do_div(wb_dirty, denominator);

	wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100;

	wb_thresh *= numerator;

	do_div(wb_thresh, denominator);



	wb_min_max_ratio(wb, &wb_min_ratio, &wb_max_ratio);



	wb_dirty += (dirty * wb_min_ratio) / 100;

	if (wb_dirty > (dirty * wb_max_ratio) / 100)

		wb_dirty = dirty * wb_max_ratio / 100;

	wb_thresh += (thresh * wb_min_ratio) / 100;

	if (wb_thresh > (thresh * wb_max_ratio) / 100)

		wb_thresh = thresh * wb_max_ratio / 100;



	return wb_dirty;

	return wb_thresh;

}



/*
@@ -750,7 +750,7 @@ static unsigned long wb_position_ratio(struct bdi_writeback *wb, 
	 * total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global

	 * limits are set by default to 10% and 20% (background and throttle).

	 * Then wb_thresh is 1% of 20% of 16GB. This amounts to ~8K pages.

	 * wb_dirty_limit(wb, bg_thresh) is about ~4K pages. wb_setpoint is

	 * wb_calc_thresh(wb, bg_thresh) is about ~4K pages. wb_setpoint is

	 * about ~6K pages (as the average of background and throttle wb

	 * limits). The 3rd order polynomial will provide positive feedback if

	 * wb_dirty is under wb_setpoint and vice versa.
@@ -1115,7 +1115,7 @@ static void wb_update_dirty_ratelimit(struct bdi_writeback *wb, 
	 *

	 * We rampup dirty_ratelimit forcibly if wb_dirty is low because

	 * it's possible that wb_thresh is close to zero due to inactivity

	 * of backing device (see the implementation of wb_dirty_limit()).

	 * of backing device (see the implementation of wb_calc_thresh()).

	 */

	if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {

		dirty = wb_dirty;
@@ -1123,7 +1123,7 @@ static void wb_update_dirty_ratelimit(struct bdi_writeback *wb, 
			setpoint = wb_dirty + 1;

		else

			setpoint = (wb_thresh +

				    wb_dirty_limit(wb, bg_thresh)) / 2;

				    wb_calc_thresh(wb, bg_thresh)) / 2;

	}



	if (dirty < setpoint) {
@@ -1352,7 +1352,7 @@ static inline void wb_dirty_limits(struct bdi_writeback *wb, 
	 *   wb_position_ratio() will let the dirtier task progress

	 *   at some rate <= (write_bw / 2) for bringing down wb_dirty.

	 */

	*wb_thresh = wb_dirty_limit(wb, dirty_thresh);

	*wb_thresh = wb_calc_thresh(wb, dirty_thresh);



	if (wb_bg_thresh)

		*wb_bg_thresh = dirty_thresh ? div_u64((u64)*wb_thresh *

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