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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: 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>
This commit is contained in:
Tejun Heo 2015-05-22 18:23:19 -04:00 committed by Jens Axboe
parent 733a572e66
commit 0d960a383a
4 changed files with 20 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/fs-writeback.c
View File

@ -1081,7 +1081,7 @@ static bool over_bground_thresh(struct bdi_writeback *wb)
global_page_state(NR_UNSTABLE_NFS) > background_thresh) global_page_state(NR_UNSTABLE_NFS) > background_thresh)
return true; 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 true;
return false; return false;

2
include/linux/writeback.h
View File

@ -155,7 +155,7 @@ int dirty_writeback_centisecs_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *); void __user *, size_t *, loff_t *);
void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); 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, void __wb_update_bandwidth(struct bdi_writeback *wb,
unsigned long thresh, unsigned long thresh,

6
mm/backing-dev.c
View File

@ -49,7 +49,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
struct bdi_writeback *wb = &bdi->wb; struct bdi_writeback *wb = &bdi->wb;
unsigned long background_thresh; unsigned long background_thresh;
unsigned long dirty_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; unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
struct inode *inode; struct inode *inode;
@ -67,7 +67,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
spin_unlock(&wb->list_lock); spin_unlock(&wb->list_lock);
global_dirty_limits(&background_thresh, &dirty_thresh); 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)) #define K(x) ((x) << (PAGE_SHIFT - 10))
seq_printf(m, seq_printf(m,
@ -87,7 +87,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
"state: %10lx\n", "state: %10lx\n",
(unsigned long) K(wb_stat(wb, WB_WRITEBACK)), (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
(unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)), (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
K(bdi_thresh), K(wb_thresh),
K(dirty_thresh), K(dirty_thresh),
K(background_thresh), K(background_thresh),
(unsigned long) K(wb_stat(wb, WB_DIRTIED)), (unsigned long) K(wb_stat(wb, WB_DIRTIED)),

30
mm/page-writeback.c
View File

@ -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 * @wb: bdi_writeback to query
* @dirty: global dirty limit in pages * @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 * 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. * 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; long numerator, denominator;
unsigned long wb_min_ratio, wb_max_ratio; 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_writeout_fraction(wb, &numerator, &denominator);
wb_dirty = (dirty * (100 - bdi_min_ratio)) / 100; wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100;
wb_dirty *= numerator; wb_thresh *= numerator;
do_div(wb_dirty, denominator); do_div(wb_thresh, denominator);
wb_min_max_ratio(wb, &wb_min_ratio, &wb_max_ratio); wb_min_max_ratio(wb, &wb_min_ratio, &wb_max_ratio);
wb_dirty += (dirty * wb_min_ratio) / 100; wb_thresh += (thresh * wb_min_ratio) / 100;
if (wb_dirty > (dirty * wb_max_ratio) / 100) if (wb_thresh > (thresh * wb_max_ratio) / 100)
wb_dirty = dirty * 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 * 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). * 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. * 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 * about ~6K pages (as the average of background and throttle wb
* limits). The 3rd order polynomial will provide positive feedback if * limits). The 3rd order polynomial will provide positive feedback if
* wb_dirty is under wb_setpoint and vice versa. * 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 * We rampup dirty_ratelimit forcibly if wb_dirty is low because
* it's possible that wb_thresh is close to zero due to inactivity * 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)) { if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
dirty = wb_dirty; dirty = wb_dirty;
@ -1123,7 +1123,7 @@ static void wb_update_dirty_ratelimit(struct bdi_writeback *wb,
setpoint = wb_dirty + 1; setpoint = wb_dirty + 1;
else else
setpoint = (wb_thresh + setpoint = (wb_thresh +
wb_dirty_limit(wb, bg_thresh)) / 2; wb_calc_thresh(wb, bg_thresh)) / 2;
} }
if (dirty < setpoint) { 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 * wb_position_ratio() will let the dirtier task progress
* at some rate <= (write_bw / 2) for bringing down wb_dirty. * 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) if (wb_bg_thresh)
*wb_bg_thresh = dirty_thresh ? div_u64((u64)*wb_thresh * *wb_bg_thresh = dirty_thresh ? div_u64((u64)*wb_thresh *