linux-kernel - [PATCH v3] f2fs: add gc_boost_gc

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Message-ID: <20250728164544.1051653-1-daeho43@gmail.com>
Date: Mon, 28 Jul 2025 09:45:44 -0700
From: Daeho Jeong <daeho43@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	kernel-team@...roid.com
Cc: Daeho Jeong <daehojeong@...gle.com>
Subject: [PATCH v3] f2fs: add gc_boost_gc_multiple sysfs node

From: Daeho Jeong <daehojeong@...gle.com>

Add a sysfs knob to set a multiplier for the background GC migration
window when F2FS Garbage Collection is boosted.

Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
---
v3: fix the range check condition
v2: limit the available value range
---
 Documentation/ABI/testing/sysfs-fs-f2fs | 8 ++++++++
 fs/f2fs/gc.c                            | 3 ++-
 fs/f2fs/gc.h                            | 1 +
 fs/f2fs/sysfs.c                         | 9 +++++++++
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index bf03263b9f46..6083119851a6 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -861,3 +861,11 @@ Description:	This is a read-only entry to show the value of sb.s_encoding_flags,
 		SB_ENC_STRICT_MODE_FL            0x00000001
 		SB_ENC_NO_COMPAT_FALLBACK_FL     0x00000002
 		============================     ==========
+
+What:		/sys/fs/f2fs/<disk>/gc_boost_gc_multiple
+Date:		June 2025
+Contact:	"Daeho Jeong" <daehojeong@...gle.com>
+Description:	Set a multiplier for the background GC migration window when F2FS GC is
+		boosted. The range should be from 1 to the segment count in a section.
+		Default: 5
+
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 3cb5242f4ddf..de7e59bc0906 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -197,6 +197,7 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 
 	gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
 	gc_th->valid_thresh_ratio = DEF_GC_THREAD_VALID_THRESH_RATIO;
+	gc_th->boost_gc_multiple = BOOST_GC_MULTIPLE;
 
 	if (f2fs_sb_has_blkzoned(sbi)) {
 		gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME_ZONED;
@@ -1749,7 +1750,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 					!has_enough_free_blocks(sbi,
 					sbi->gc_thread->boost_zoned_gc_percent))
 				window_granularity *=
-					BOOST_GC_MULTIPLE;
+					sbi->gc_thread->boost_gc_multiple;
 
 			end_segno = start_segno + window_granularity;
 		}
diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
index 5c1eaf55e127..efa1968810a0 100644
--- a/fs/f2fs/gc.h
+++ b/fs/f2fs/gc.h
@@ -68,6 +68,7 @@ struct f2fs_gc_kthread {
 	unsigned int no_zoned_gc_percent;
 	unsigned int boost_zoned_gc_percent;
 	unsigned int valid_thresh_ratio;
+	unsigned int boost_gc_multiple;
 };
 
 struct gc_inode_list {
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 75134d69a0bd..b417b655d4e8 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -824,6 +824,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
+	if (!strcmp(a->attr.name, "gc_boost_gc_multiple")) {
+		if (t < 1 || t > SEGS_PER_SEC(sbi))
+			return -EINVAL;
+		sbi->gc_thread->boost_gc_multiple = (unsigned int)t;
+		return count;
+	}
+
 	*ui = (unsigned int)t;
 
 	return count;
@@ -1050,6 +1057,7 @@ GC_THREAD_RW_ATTR(gc_no_gc_sleep_time, no_gc_sleep_time);
 GC_THREAD_RW_ATTR(gc_no_zoned_gc_percent, no_zoned_gc_percent);
 GC_THREAD_RW_ATTR(gc_boost_zoned_gc_percent, boost_zoned_gc_percent);
 GC_THREAD_RW_ATTR(gc_valid_thresh_ratio, valid_thresh_ratio);
+GC_THREAD_RW_ATTR(gc_boost_gc_multiple, boost_gc_multiple);
 
 /* SM_INFO ATTR */
 SM_INFO_RW_ATTR(reclaim_segments, rec_prefree_segments);
@@ -1220,6 +1228,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(gc_no_zoned_gc_percent),
 	ATTR_LIST(gc_boost_zoned_gc_percent),
 	ATTR_LIST(gc_valid_thresh_ratio),
+	ATTR_LIST(gc_boost_gc_multiple),
 	ATTR_LIST(gc_idle),
 	ATTR_LIST(gc_urgent),
 	ATTR_LIST(reclaim_segments),
-- 
2.50.1.487.gc89ff58d15-goog