2024-04-29 03:48:05

by Kemeng Shi

Subject: [PATCH 01/10] writeback: factor out wb_bg_dirty_limits to remove repeated code

Similar to wb_dirty_limits which calculates dirty and thresh of wb,
wb_bg_dirty_limits calculates background dirty and background thresh of
wb. With wb_bg_dirty_limits, we could remove repeated code in
wb_over_bg_thresh.

Signed-off-by: Kemeng Shi <[email protected]>
---
mm/page-writeback.c | 35 +++++++++++++++++++----------------
1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 692c0da04cbd..e1f73643aca1 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2087,6 +2087,21 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping)
}
EXPORT_SYMBOL(balance_dirty_pages_ratelimited);

+/*
+ * Similar to wb_dirty_limits, wb_bg_dirty_limits also calculates dirty
+ * and thresh, but it's for background writeback.
+ */
+static void wb_bg_dirty_limits(struct dirty_throttle_control *dtc)
+{
+ struct bdi_writeback *wb = dtc->wb;
+
+ dtc->wb_bg_thresh = __wb_calc_thresh(dtc, dtc->bg_thresh);
+ if (dtc->wb_bg_thresh < 2 * wb_stat_error())
+ dtc->wb_dirty = wb_stat_sum(wb, WB_RECLAIMABLE);
+ else
+ dtc->wb_dirty = wb_stat(wb, WB_RECLAIMABLE);
+}
+
/**
* wb_over_bg_thresh - does @wb need to be written back?
* @wb: bdi_writeback of interest
@@ -2103,8 +2118,6 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb)
struct dirty_throttle_control * const gdtc = &gdtc_stor;
struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ?
&mdtc_stor : NULL;
- unsigned long reclaimable;
- unsigned long thresh;

/*
* Similar to balance_dirty_pages() but ignores pages being written
@@ -2117,13 +2130,8 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb)
if (gdtc->dirty > gdtc->bg_thresh)
return true;

- thresh = __wb_calc_thresh(gdtc, gdtc->bg_thresh);
- if (thresh < 2 * wb_stat_error())
- reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE);
- else
- reclaimable = wb_stat(wb, WB_RECLAIMABLE);
-
- if (reclaimable > thresh)
+ wb_bg_dirty_limits(gdtc);
+ if (gdtc->wb_dirty > gdtc->wb_bg_thresh)
return true;

if (mdtc) {
@@ -2137,13 +2145,8 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb)
if (mdtc->dirty > mdtc->bg_thresh)
return true;

- thresh = __wb_calc_thresh(mdtc, mdtc->bg_thresh);
- if (thresh < 2 * wb_stat_error())
- reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE);
- else
- reclaimable = wb_stat(wb, WB_RECLAIMABLE);
-
- if (reclaimable > thresh)
+ wb_bg_dirty_limits(mdtc);
+ if (mdtc->wb_dirty > mdtc->wb_bg_thresh)
return true;
}

--
2.30.0

2024-05-01 16:41:05

by Tejun Heo

Subject: Re: [PATCH 01/10] writeback: factor out wb_bg_dirty_limits to remove repeated code

On Mon, Apr 29, 2024 at 11:47:29AM +0800, Kemeng Shi wrote:
> Similar to wb_dirty_limits which calculates dirty and thresh of wb,
> wb_bg_dirty_limits calculates background dirty and background thresh of
> wb. With wb_bg_dirty_limits, we could remove repeated code in
> wb_over_bg_thresh.
>
> Signed-off-by: Kemeng Shi <[email protected]>

Acked-by: Tejun Heo <[email protected]>

Thanks.

--
tejun