Subject: Date: Wed Sep 14 22:57:43 CST 2011 Signed-off-by: Wu Fengguang --- mm/page-writeback.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) --- linux-next.orig/mm/page-writeback.c 2011-09-14 22:50:33.000000000 +0800 +++ linux-next/mm/page-writeback.c 2011-09-14 22:58:15.000000000 +0800 @@ -614,22 +614,6 @@ static unsigned long bdi_position_ratio( } 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. It's not necessary in single-bdi case because a - * minimal pool of @freerun dirty pages will already be guaranteed. - */ - x_intercept = min(write_bw, freerun); - 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; } @@ -1089,8 +1073,14 @@ static void balance_dirty_pages(struct a nr_dirty, bdi_thresh, bdi_dirty, start_time); - if (unlikely(!dirty_exceeded && bdi_async_underrun(bdi))) - break; + freerun = min(bdi->avg_write_bandwidth + MIN_WRITEBACK_PAGES, + global_dirty_limit - nr_dirty) / 8; + if (!dirty_exceeded) { + if (unlikely(bdi_dirty < freerun)) + break; + if (unlikely(bdi_async_underrun(bdi))) + break; + } max_pause = bdi_max_pause(bdi, bdi_dirty);