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From: Tejun Heo <tj@kernel.org>
To: axboe@kernel.dk
Cc: linux-kernel@vger.kernel.org, jack@suse.cz, hch@infradead.org,
	hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org,
	vgoyal@redhat.com, lizefan@huawei.com, cgroups@vger.kernel.org,
	linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com,
	fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com,
	Tejun Heo <tj@kernel.org>
Subject: [PATCH 02/19] writeback: clean up wb_dirty_limit()
Date: Mon,  6 Apr 2015 16:04:17 -0400	[thread overview]
Message-ID: <1428350674-8303-3-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1428350674-8303-1-git-send-email-tj@kernel.org>

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>
---
 fs/fs-writeback.c         |  2 +-
 include/linux/writeback.h |  2 +-
 mm/backing-dev.c          |  6 +++---
 mm/page-writeback.c       | 30 +++++++++++++++---------------
 4 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 2b9c82b..2b6df69 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1062,7 +1062,7 @@ 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;
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 75349bb..6f6b8c8 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -152,7 +152,7 @@ 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,
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index ad5608d..9c8b7b5 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -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)),
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 1767658..3401634 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -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 *
-- 
2.1.0

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  parent reply	other threads:[~2015-04-06 20:04 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-06 20:04 [PATCHSET 2/3 v2 block/for-4.1/core] writeback: cgroup writeback backpressure propagation Tejun Heo
2015-04-06 20:04 ` [PATCH 01/19] memcg: make mem_cgroup_read_{stat|event}() iterate possible cpus instead of online Tejun Heo
2015-04-06 20:04 ` Tejun Heo [this message]
2015-04-06 20:04 ` [PATCH 03/19] writeback: reorganize [__]wb_update_bandwidth() Tejun Heo
2015-04-06 20:04 ` [PATCH 04/19] writeback: implement wb_domain Tejun Heo
2015-04-06 20:04 ` [PATCH 05/19] writeback: move global_dirty_limit into wb_domain Tejun Heo
2015-04-06 20:04 ` [PATCH 06/19] writeback: consolidate dirty throttle parameters into dirty_throttle_control Tejun Heo
2015-04-06 20:04 ` [PATCH 07/19] writeback: add dirty_throttle_control->wb_bg_thresh Tejun Heo
2015-04-06 20:04 ` [PATCH 08/19] writeback: make __wb_calc_thresh() take dirty_throttle_control Tejun Heo
2015-04-06 20:04 ` [PATCH 09/19] writeback: add dirty_throttle_control->pos_ratio Tejun Heo
2015-04-06 20:04 ` [PATCH 10/19] writeback: add dirty_throttle_control->wb_completions Tejun Heo
2015-04-06 20:04 ` [PATCH 11/19] writeback: add dirty_throttle_control->dom Tejun Heo
2015-04-06 20:04 ` [PATCH 12/19] writeback: make __wb_writeout_inc() and hard_dirty_limit() take wb_domaas a parameter Tejun Heo
2015-04-06 20:04 ` [PATCH 13/19] writeback: separate out domain_dirty_limits() Tejun Heo
2015-04-06 20:04 ` [PATCH 14/19] writeback: move over_bground_thresh() to mm/page-writeback.c Tejun Heo
2015-04-06 20:04 ` [PATCH 15/19] writeback: update wb_over_bg_thresh() to use wb_domain aware operations Tejun Heo
2015-04-06 20:04 ` [PATCH 16/19] writeback: implement memcg wb_domain Tejun Heo
2015-04-06 20:04 ` [PATCH 17/19] writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes Tejun Heo
2015-04-06 20:04 ` [PATCH 18/19] writeback: implement memcg writeback domain based throttling Tejun Heo
2015-04-06 20:04 ` [PATCH 19/19] mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use Tejun Heo
2015-04-06 20:07 ` [PATCHSET 2/3 v2 block/for-4.1/core] writeback: cgroup writeback backpressure propagation Tejun Heo
2015-05-22 22:23 [PATCHSET 2/3 v3 block/for-4.2/core] " Tejun Heo
2015-05-22 22:23 ` [PATCH 02/19] writeback: clean up wb_dirty_limit() Tejun Heo

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