linux-kernel - [PATCH V3] f2fs: fix to avoid use GC_AT when setting gc_mode as GC_URGENT_LOW or GC_URGENT

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Message-ID: <1730171569-10757-1-git-send-email-zhiguo.niu@unisoc.com>
Date: Tue, 29 Oct 2024 11:12:49 +0800
From: Zhiguo Niu <zhiguo.niu@...soc.com>
To: <jaegeuk@...nel.org>, <chao@...nel.org>
CC: <linux-f2fs-devel@...ts.sourceforge.net>, <linux-kernel@...r.kernel.org>,
        <niuzhiguo84@...il.com>, <zhiguo.niu@...soc.com>, <ke.wang@...soc.com>,
        <Hao_hao.Wang@...soc.com>
Subject: [PATCH V3] f2fs: fix to avoid use GC_AT when setting gc_mode as GC_URGENT_LOW or GC_URGENT_MID

If gc_mode is set to GC_URGENT_LOW or GC_URGENT_MID, cost benefit GC
approach should be used, but if ATGC is enabled at the same time,
Age-threshold approach will be selected, which can only do amount of
GC and it is much less than the numbers of CB approach.

some traces:
  f2fs_gc-254:48-396     [007] ..... 2311600.684028: f2fs_gc_begin: dev = (254,48), gc_type = Background GC, no_background_GC = 0, nr_free_secs = 0, nodes = 1053, dents = 2, imeta = 18, free_sec:44898, free_seg:44898, rsv_seg:239, prefree_seg:0
  f2fs_gc-254:48-396     [007] ..... 2311600.684527: f2fs_get_victim: dev = (254,48), type = No TYPE, policy = (Background GC, LFS-mode, Age-threshold), victim = 10, cost = 4294364975, ofs_unit = 1, pre_victim_secno = -1, prefree = 0, free = 44898
  f2fs_gc-254:48-396     [007] ..... 2311600.714835: f2fs_gc_end: dev = (254,48), ret = 0, seg_freed = 0, sec_freed = 0, nodes = 1562, dents = 2, imeta = 18, free_sec:44898, free_seg:44898, rsv_seg:239, prefree_seg:0
  f2fs_gc-254:48-396     [007] ..... 2311600.714843: f2fs_background_gc: dev = (254,48), wait_ms = 50, prefree = 0, free = 44898
  f2fs_gc-254:48-396     [007] ..... 2311600.771785: f2fs_gc_begin: dev = (254,48), gc_type = Background GC, no_background_GC = 0, nr_free_secs = 0, nodes = 1562, dents = 2, imeta = 18, free_sec:44898, free_seg:44898, rsv_seg:239, prefree_seg:
  f2fs_gc-254:48-396     [007] ..... 2311600.772275: f2fs_gc_end: dev = (254,48), ret = -61, seg_freed = 0, sec_freed = 0, nodes = 1562, dents = 2, imeta = 18, free_sec:44898, free_seg:44898, rsv_seg:239, prefree_seg:0

Fixes: 0e5e81114de1 ("f2fs: add GC_URGENT_LOW mode in gc_urgent")
Fixes: d98af5f45520 ("f2fs: introduce gc_urgent_mid mode")
Signed-off-by: Zhiguo Niu <zhiguo.niu@...soc.com>
---
v3: add more descriptions in sys-fs-f2fs for gc_urgent(2) and gc_urgent(3)
v2: make GC_URGENT_LOW also use CB approach
---
 Documentation/ABI/testing/sysfs-fs-f2fs | 7 +++++--
 fs/f2fs/gc.c                            | 2 ++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index fdedf1e..513296b 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -311,10 +311,13 @@ Description:	Do background GC aggressively when set. Set to 0 by default.
 		GC approach and turns SSR mode on.
 		gc urgent low(2): lowers the bar of checking I/O idling in
 		order to process outstanding discard commands and GC a
-		little bit aggressively. uses cost benefit GC approach.
+		little bit aggressively. always uses cost benefit GC approach,
+		and will override age-threshold GC approach if ATGC is enabled
+		at the same time.
 		gc urgent mid(3): does GC forcibly in a period of given
 		gc_urgent_sleep_time and executes a mid level of I/O idling check.
-		uses cost benefit GC approach.
+		always uses cost benefit GC approach, and will override
+		age-threshold GC approach if ATGC is enabled at the same time.
 
 What:		/sys/fs/f2fs/<disk>/gc_urgent_sleep_time
 Date:		August 2017
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index e40bdd1..3e1b6d2 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -257,6 +257,8 @@ static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
 
 	switch (sbi->gc_mode) {
 	case GC_IDLE_CB:
+	case GC_URGENT_LOW:
+	case GC_URGENT_MID:
 		gc_mode = GC_CB;
 		break;
 	case GC_IDLE_GREEDY:
-- 
1.9.1