Currently, we have encountered some issues while testing ZUFS. In
situations near the storage limit (e.g., 50GB remaining), and after
simulating fragmentation by repeatedly writing and deleting data, we found
that application installation and startup tests conducted after idling for
a few minutes take significantly longer several times that of traditional
UFS. Tracing the operations revealed that the majority of I/Os were issued
by background GC, which blocks normal I/O operations.
Under normal circumstances, ZUFS indeed requires more background GC and
employs a more aggressive GC strategy. However, I aim to find a way to
minimize the impact on regular I/O operations under these near-limit
conditions. To address this, I have introduced a bggc_block_io feature,
which controls the prioritization of background GC in the presence of I/Os.
This switch can be adjusted at the framework level to implement different
strategies. If set to ALL_IO_PRIOR, all background GC operations will be
skipped during active I/O issuance. The default option remains consistent
with the current strategy, ensuring no change in behavior.
---
Changes in v3:
Modified the issue where it does not work after closing
CONFIG_BLK_DEV_ZONED.
Changes in v2:
Non ZUFS can also be adjusted through this option.
Signed-off-by: Liao Yuanhong <liaoyuanh...@vivo.com>
---
Documentation/ABI/testing/sysfs-fs-f2fs | 13 +++++++++++++
fs/f2fs/f2fs.h | 18 +++++++++++-------
fs/f2fs/super.c | 2 ++
fs/f2fs/sysfs.c | 9 +++++++++
4 files changed, 35 insertions(+), 7 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs
b/Documentation/ABI/testing/sysfs-fs-f2fs
index bc0e7fefc39d..12fda11d4da5 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -883,3 +883,16 @@ Date: June 2025
Contact: "Daeho Jeong" <daehoje...@google.com>
Description: Control GC algorithm for boost GC. 0: cost benefit, 1: greedy
Default: 1
+
+What: /sys/fs/f2fs/<disk>/bggc_block_io
+Date: August 2025
+Contact: "Liao Yuanhong" <liaoyuanh...@vivo.com>
+Description: Used to adjust the BG_GC priority when issuing IO, with a
default value
+ of 1.
+
+ ==================
=============================================
+ value description
+ bggc_block_io = 0 Prioritize background GC
+ bggc_block_io = 1 Stop background GC only when issuing read
I/O
+ bggc_block_io = 2 Stop background GC when issuing I/O
+ ==================
=============================================
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 46be7560548c..fe41b733fbc2 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -155,6 +155,12 @@ enum blkzone_allocation_policy {
BLKZONE_ALLOC_PRIOR_CONV, /* Prioritize writing to conventional
zones */
};
+enum bggc_block_io_policy {
+ BGGC_PRIOR,
+ READ_IO_PRIOR,
+ ALL_IO_PRIOR,
+};
+
/*
* An implementation of an rwsem that is explicitly unfair to readers. This
* prevents priority inversion when a low-priority reader acquires the read
lock
@@ -1804,6 +1810,7 @@ struct f2fs_sb_info {
spinlock_t dev_lock; /* protect dirty_device */
bool aligned_blksize; /* all devices has the same
logical blksize */
unsigned int first_seq_zone_segno; /* first segno in sequential
zone */
+ unsigned int bggc_block_io; /* For adjust the BG_GC
priority when issuing IO */
/* For write statistics */
u64 sectors_written_start;
@@ -2998,13 +3005,10 @@ static inline bool is_idle(struct f2fs_sb_info *sbi,
int type)
if (sbi->gc_mode == GC_URGENT_HIGH)
return true;
- if (zoned_gc) {
- if (is_inflight_read_io(sbi))
- return false;
- } else {
- if (is_inflight_io(sbi, type))
- return false;
- }
+ if (sbi->bggc_block_io == READ_IO_PRIOR && is_inflight_read_io(sbi))
+ return false;
+ if (sbi->bggc_block_io == ALL_IO_PRIOR && is_inflight_io(sbi, type))
+ return false;
if (sbi->gc_mode == GC_URGENT_MID)
return true;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index e16c4e2830c2..a21cecc5424e 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -4629,9 +4629,11 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
logical_blksize = bdev_logical_block_size(sbi->sb->s_bdev);
sbi->aligned_blksize = true;
+ sbi->bggc_block_io = ALL_IO_PRIOR;
#ifdef CONFIG_BLK_DEV_ZONED
sbi->max_open_zones = UINT_MAX;
sbi->blkzone_alloc_policy = BLKZONE_ALLOC_PRIOR_SEQ;
+ sbi->bggc_block_io = READ_IO_PRIOR;
#endif
for (i = 0; i < max_devices; i++) {
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index f736052dea50..381f29ae90fc 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -866,6 +866,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
return count;
}
+ if (!strcmp(a->attr.name, "bggc_block_io")) {
+ if (t < BGGC_PRIOR || t > ALL_IO_PRIOR)
+ return -EINVAL;
+ sbi->bggc_block_io = t;
+ return count;
+ }
+
*ui = (unsigned int)t;
return count;
@@ -1175,6 +1182,7 @@ F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
#endif
F2FS_SBI_GENERAL_RW_ATTR(carve_out);
F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section);
+F2FS_SBI_GENERAL_RW_ATTR(bggc_block_io);
/* STAT_INFO ATTR */
#ifdef CONFIG_F2FS_STAT_FS
@@ -1303,6 +1311,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(discard_idle_interval),
ATTR_LIST(gc_idle_interval),
ATTR_LIST(umount_discard_timeout),
+ ATTR_LIST(bggc_block_io),
#ifdef CONFIG_F2FS_IOSTAT
ATTR_LIST(iostat_enable),
ATTR_LIST(iostat_period_ms),
--
2.34.1
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