diff options
Diffstat (limited to 'mm/page-writeback.c')
| -rw-r--r-- | mm/page-writeback.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 6a8bb693b429..325f753c80ed 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -599,6 +599,7 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi, */ if (unlikely(bdi_thresh > thresh)) bdi_thresh = thresh; + bdi_thresh = max(bdi_thresh, (limit - dirty) / 8); /* * scale global setpoint to bdi's: * bdi_setpoint = setpoint * bdi_thresh / thresh @@ -622,6 +623,20 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi, } else pos_ratio /= 4; + /* + * bdi reserve area, safeguard against dirty pool underrun and disk idle + * It may push the desired control point of global dirty pages higher + * than setpoint. + */ + x_intercept = bdi_thresh / 2; + if (bdi_dirty < x_intercept) { + if (bdi_dirty > x_intercept / 8) { + pos_ratio *= x_intercept; + do_div(pos_ratio, bdi_dirty); + } else + pos_ratio *= 8; + } + return pos_ratio; } |