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Commit d73a7033 authored by Sahitya Tummala's avatar Sahitya Tummala
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f2fs: allow to change discard policy based on cached discard cmds 



With the default DPOLICY_BG discard thread is ioaware, which prevents
the discard thread from issuing the discard commands. On low RAM setups,
it is observed that these discard commands in the cache are consuming
high memory. This patch aims to relax the memory pressure on the system
due to f2fs pending discard cmds by changing the policy to DPOLICY_FORCE
based on the nm_i->ram_thresh configured.

Change-Id: I01b692df6f0ecdf92e316d3cea764d87d5f73ffe
Signed-off-by: default avatarSahitya Tummala <stummala@codeaurora.org>
parent 4440785e

fs/f2fs/node.c

+8 −0
Original line number Diff line number Diff line
@@ -44,11 +44,15 @@ int f2fs_check_nid_range(struct f2fs_sb_info *sbi, nid_t nid) 
bool f2fs_available_free_memory(struct f2fs_sb_info *sbi, int type)

{

	struct f2fs_nm_info *nm_i = NM_I(sbi);

	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;

	struct sysinfo val;

	unsigned long avail_ram;

	unsigned long mem_size = 0;

	bool res = false;



	if (!nm_i)

		return true;



	si_meminfo(&val);



	/* only uses low memory */
@@ -90,6 +94,10 @@ bool f2fs_available_free_memory(struct f2fs_sb_info *sbi, int type) 
		/* it allows 20% / total_ram for inmemory pages */

		mem_size = get_pages(sbi, F2FS_INMEM_PAGES);

		res = mem_size < (val.totalram / 5);

	} else if (type == DISCARD_CACHE) {

		mem_size = (atomic_read(&dcc->discard_cmd_cnt) *

				sizeof(struct discard_cmd)) >> PAGE_SHIFT;

		res = mem_size < (avail_ram * nm_i->ram_thresh / 100);

	} else {

		if (!sbi->sb->s_bdi->wb.dirty_exceeded)

			return true;

fs/f2fs/node.h

+1 −0
Original line number Diff line number Diff line
@@ -147,6 +147,7 @@ enum mem_type { 
	INO_ENTRIES,	/* indicates inode entries */

	EXTENT_CACHE,	/* indicates extent cache */

	INMEM_PAGES,	/* indicates inmemory pages */

	DISCARD_CACHE,	/* indicates memory of cached discard cmds */

	BASE_CHECK,	/* check kernel status */

};

fs/f2fs/segment.c

+2 −1
Original line number Diff line number Diff line
@@ -1733,7 +1733,8 @@ static int issue_discard_thread(void *data) 
			continue;

		}



		if (sbi->gc_mode == GC_URGENT)

		if (sbi->gc_mode == GC_URGENT ||

			!f2fs_available_free_memory(sbi, DISCARD_CACHE))

			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);



		sb_start_intwrite(sbi->sb);