Commit 9bb48a70 authored by Kemeng Shi's avatar Kemeng Shi Committed by Andrew Morton
Browse files

writeback: factor out code of freerun to remove repeated code 

Factor out code of freerun into new helper functions domain_poll_intv and
domain_dirty_freerun to remove repeated code.

Link: https://lkml.kernel.org/r/20240514125254.142203-5-shikemeng@huaweicloud.com


Signed-off-by: default avatarKemeng Shi <shikemeng@huaweicloud.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 6e208329

mm/page-writeback.c

+49 −40
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ struct dirty_throttle_control { 
	unsigned long		wb_bg_thresh;



	unsigned long		pos_ratio;

	bool			freerun;

};



/*
@@ -1702,6 +1703,49 @@ static inline void wb_dirty_limits(struct dirty_throttle_control *dtc) 
	}

}



static unsigned long domain_poll_intv(struct dirty_throttle_control *dtc,

				      bool strictlimit)

{

	unsigned long dirty, thresh;



	if (strictlimit) {

		dirty = dtc->wb_dirty;

		thresh = dtc->wb_thresh;

	} else {

		dirty = dtc->dirty;

		thresh = dtc->thresh;

	}



	return dirty_poll_interval(dirty, thresh);

}



/*

 * Throttle it only when the background writeback cannot catch-up. This avoids

 * (excessively) small writeouts when the wb limits are ramping up in case of

 * !strictlimit.

 *

 * In strictlimit case make decision based on the wb counters and limits. Small

 * writeouts when the wb limits are ramping up are the price we consciously pay

 * for strictlimit-ing.

 */

static void domain_dirty_freerun(struct dirty_throttle_control *dtc,

				 bool strictlimit)

{

	unsigned long dirty, thresh, bg_thresh;



	if (unlikely(strictlimit)) {

		wb_dirty_limits(dtc);

		dirty = dtc->wb_dirty;

		thresh = dtc->wb_thresh;

		bg_thresh = dtc->wb_bg_thresh;

	} else {

		dirty = dtc->dirty;

		thresh = dtc->thresh;

		bg_thresh = dtc->bg_thresh;

	}

	dtc->freerun = dirty <= dirty_freerun_ceiling(thresh, bg_thresh);

}



/*

 * balance_dirty_pages() must be called by processes which are generating dirty

 * data.  It looks at the number of dirty pages in the machine and will force
@@ -1734,27 +1778,12 @@ static int balance_dirty_pages(struct bdi_writeback *wb, 


	for (;;) {

		unsigned long now = jiffies;

		unsigned long dirty, thresh, bg_thresh;

		unsigned long m_dirty = 0;	/* stop bogus uninit warnings */

		unsigned long m_thresh = 0;

		unsigned long m_bg_thresh = 0;



		nr_dirty = global_node_page_state(NR_FILE_DIRTY);



		domain_dirty_avail(gdtc, true);

		domain_dirty_limits(gdtc);



		if (unlikely(strictlimit)) {

			wb_dirty_limits(gdtc);



			dirty = gdtc->wb_dirty;

			thresh = gdtc->wb_thresh;

			bg_thresh = gdtc->wb_bg_thresh;

		} else {

			dirty = gdtc->dirty;

			thresh = gdtc->thresh;

			bg_thresh = gdtc->bg_thresh;

		}

		domain_dirty_freerun(gdtc, strictlimit);



		if (mdtc) {

			/*
@@ -1763,17 +1792,7 @@ static int balance_dirty_pages(struct bdi_writeback *wb, 
			 */

			domain_dirty_avail(mdtc, true);

			domain_dirty_limits(mdtc);



			if (unlikely(strictlimit)) {

				wb_dirty_limits(mdtc);

				m_dirty = mdtc->wb_dirty;

				m_thresh = mdtc->wb_thresh;

				m_bg_thresh = mdtc->wb_bg_thresh;

			} else {

				m_dirty = mdtc->dirty;

				m_thresh = mdtc->thresh;

				m_bg_thresh = mdtc->bg_thresh;

			}

			domain_dirty_freerun(mdtc, strictlimit);

		}



		/*
@@ -1790,31 +1809,21 @@ static int balance_dirty_pages(struct bdi_writeback *wb, 
			wb_start_background_writeback(wb);



		/*

		 * Throttle it only when the background writeback cannot

		 * catch-up. This avoids (excessively) small writeouts

		 * when the wb limits are ramping up in case of !strictlimit.

		 *

		 * In strictlimit case make decision based on the wb counters

		 * and limits. Small writeouts when the wb limits are ramping

		 * up are the price we consciously pay for strictlimit-ing.

		 *

		 * If memcg domain is in effect, @dirty should be under

		 * both global and memcg freerun ceilings.

		 */

		if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh) &&

		    (!mdtc ||

		     m_dirty <= dirty_freerun_ceiling(m_thresh, m_bg_thresh))) {

		if (gdtc->freerun && (!mdtc || mdtc->freerun)) {

			unsigned long intv;

			unsigned long m_intv;



free_running:

			intv = dirty_poll_interval(dirty, thresh);

			intv = domain_poll_intv(gdtc, strictlimit);

			m_intv = ULONG_MAX;



			current->dirty_paused_when = now;

			current->nr_dirtied = 0;

			if (mdtc)

				m_intv = dirty_poll_interval(m_dirty, m_thresh);

				m_intv = domain_poll_intv(mdtc, strictlimit);

			current->nr_dirtied_pause = min(intv, m_intv);

			break;

		}