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Commit 24971066 authored by Sahitya Tummala's avatar Sahitya Tummala Committed by Sayali Lokhande
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f2fs: fix the periodic wakeups of discard thread 



Fix the unnecessary periodic wakeups of discard thread that happens under
below two conditions -

1. When f2fs is heavily utilized over 80%, the current discard policy
sets the max sleep timeout of discard thread as 50ms
(DEF_MIN_DISCARD_ISSUE_TIME). But this is set even when there are
no pending discard commands to be issued.

2. In the issue_discard_thread() path when there are no pending discard
commands, it fails to reset the wait_ms to max timeout value.

Change-Id: Ic358ea425a1e152438eb3185e6b7932c7fd4930f
Signed-off-by: default avatarSahitya Tummala <stummala@codeaurora.org>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
Git-commit: c35b8d5e757e0fd0144890b7b536f7b756f3a648
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: default avatarSayali Lokhande <sayalil@codeaurora.org>
parent 03858488

fs/f2fs/segment.c

+14 −7
Original line number Diff line number Diff line
@@ -1072,6 +1072,8 @@ static void __init_discard_policy(struct f2fs_sb_info *sbi, 
				struct discard_policy *dpolicy,

				int discard_type, unsigned int granularity)

{

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



	/* common policy */

	dpolicy->type = discard_type;

	dpolicy->sync = true;
@@ -1091,7 +1093,9 @@ static void __init_discard_policy(struct f2fs_sb_info *sbi, 
		dpolicy->ordered = true;

		if (utilization(sbi) > DEF_DISCARD_URGENT_UTIL) {

			dpolicy->granularity = 1;

			dpolicy->max_interval = DEF_MIN_DISCARD_ISSUE_TIME;

			if (atomic_read(&dcc->discard_cmd_cnt))

				dpolicy->max_interval =

					DEF_MIN_DISCARD_ISSUE_TIME;

		}

	} else if (discard_type == DPOLICY_FORCE) {

		dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
@@ -1707,9 +1711,16 @@ static int issue_discard_thread(void *data) 
	set_freezable();



	do {

		if (sbi->gc_mode == GC_URGENT ||

			!f2fs_available_free_memory(sbi, DISCARD_CACHE))

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

		else

			__init_discard_policy(sbi, &dpolicy, DPOLICY_BG,

						dcc->discard_granularity);



		if (!atomic_read(&dcc->discard_cmd_cnt))

			wait_ms = dpolicy.max_interval;



		wait_event_interruptible_timeout(*q,

				kthread_should_stop() || freezing(current) ||

				dcc->discard_wake,
@@ -1733,10 +1744,6 @@ static int issue_discard_thread(void *data) 
			continue;

		}



		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);



		issued = __issue_discard_cmd(sbi, &dpolicy);