linux-master/mm/page-writeback.c

134 	unsigned long		thresh;		/* dirty threshold */
367  * domain_dirty_limits - calculate thresh and bg_thresh for a wb_domain
370  * Calculate @dtc->thresh and ->bg_thresh considering
384 	unsigned long thresh;
409 		thresh = DIV_ROUND_UP(bytes, PAGE_SIZE);
411 		thresh = (ratio * available_memory) / PAGE_SIZE;
418 	if (bg_thresh >= thresh)
419 		bg_thresh = thresh / 2;
423 		thresh += thresh / 4 + global_wb_domain.dirty_limit / 32;
425 	dtc->thresh = thresh;
430 		trace_global_dirty_state(bg_thresh, thresh);
436  * @pdirty: out parameter for thresh
438  * Calculate bg_thresh and thresh for global_wb_domain.  See
449 	*pdirty = gdtc.thresh;
813 static unsigned long dirty_freerun_ceiling(unsigned long thresh,
816 	return (thresh + bg_thresh) / 2;
820 				      unsigned long thresh)
822 	return max(thresh, dom->dirty_limit);
864 	unsigned long thresh = dtc->thresh;
870 	 * Calculate this BDI's share of the thresh ratio.
875 	wb_thresh = (thresh * (100 * BDI_RATIO_SCALE - bdi_min_ratio)) / (100 * BDI_RATIO_SCALE);
881 	wb_thresh += (thresh * wb_min_ratio) / (100 * BDI_RATIO_SCALE);
882 	if (wb_thresh > (thresh * wb_max_ratio) / (100 * BDI_RATIO_SCALE))
883 		wb_thresh = thresh * wb_max_ratio / (100 * BDI_RATIO_SCALE);
888 unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh)
891 					       .thresh = thresh };
999  * - the wb dirty thresh drops quickly due to change of JBOD workload
1005 	unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh);
1006 	unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh);
1130 	if (unlikely(wb_thresh > dtc->thresh))
1131 		wb_thresh = dtc->thresh;
1142 	 *	wb_setpoint = setpoint * wb_thresh / thresh
1144 	x = div_u64((u64)wb_thresh << 16, dtc->thresh | 1);
1148 	 * (thresh - wb_thresh ~= 0) and transit to wb_thresh in JBOD case.
1150 	 *        wb_thresh                    thresh - wb_thresh
1152 	 *         thresh                           thresh
1154 	span = (dtc->thresh - wb_thresh + 8 * write_bw) * (u64)x >> 16;
1233 	unsigned long thresh = dtc->thresh;
1239 	if (limit < thresh) {
1240 		limit = thresh;
1245 	 * Follow down slowly. Use the higher one as the target, because thresh
1249 	thresh = max(thresh, dtc->dirty);
1250 	if (limit > thresh) {
1251 		limit -= (limit - thresh) >> 5;
1290 	unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh);
1291 	unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh);
1519 					 unsigned long thresh)
1521 	if (thresh > dirty)
1522 		return 1UL << (ilog2(thresh - dirty) >> 1);
1640 	dtc->wb_bg_thresh = dtc->thresh ?
1641 		div64_u64(dtc->wb_thresh * dtc->bg_thresh, dtc->thresh) : 0;
1648 	 * Otherwise it would be possible to get thresh+n pages
1649 	 * reported dirty, even though there are thresh-m pages
1694 		unsigned long dirty, thresh, bg_thresh;
1709 			thresh = gdtc->wb_thresh;
1713 			thresh = gdtc->thresh;
1738 				m_thresh = mdtc->thresh;
1768 		if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh) &&
1775 			intv = dirty_poll_interval(dirty, thresh);
1811 			((gdtc->dirty > gdtc->thresh) || strictlimit);
1838 				((mdtc->dirty > mdtc->thresh) || strictlimit);
1879 						  sdtc->thresh,
1908 					  sdtc->thresh,
1932 		 * This is typically equal to (dirty < thresh) and can also
2085 	unsigned long thresh;
2098 	thresh = wb_calc_thresh(gdtc->wb, gdtc->bg_thresh);
2099 	if (thresh < 2 * wb_stat_error())
2104 	if (reclaimable > thresh)
2118 		thresh = wb_calc_thresh(mdtc->wb, mdtc->bg_thresh);
2119 		if (thresh < 2 * wb_stat_error())
2124 		if (reclaimable > thresh)