linux-kernel - [PATCH 2/5] f2fs: add auto tuning for small devices

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Date:   Mon, 26 Feb 2018 09:47:28 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 2/5] f2fs: add auto tuning for small devices

If f2fs is running on top of very small devices, it's worth to avoid abusing
free LBAs. In order to achieve that, this patch introduces some parameter
tuning.

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 fs/f2fs/segment.h |  2 ++
 fs/f2fs/super.c   | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index f11c4bc82c78..dbb774aaf387 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -596,6 +596,8 @@ static inline int utilization(struct f2fs_sb_info *sbi)
 #define DEF_MIN_FSYNC_BLOCKS	8
 #define DEF_MIN_HOT_BLOCKS	16
 
+#define SMALL_VOLUME_SEGMENTS	(16 * 512)	/* 16GB */
+
 enum {
 	F2FS_IPU_FORCE,
 	F2FS_IPU_SSR,
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index b7c0bdd1e532..9515c10eebad 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2512,6 +2512,18 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 	return 0;
 }
 
+static void f2fs_tuning_parameters(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_sm_info *sm_i = SM_I(sbi);
+
+	/* adjust parameters according to the volume size */
+	if (sm_i->main_segments <= SMALL_VOLUME_SEGMENTS) {
+		sbi->alloc_mode = ALLOC_MODE_REUSE;
+		sm_i->dcc_info->discard_granularity = 1;
+		sm_i->ipu_policy = 1 << F2FS_IPU_FORCE;
+	}
+}
+
 static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct f2fs_sb_info *sbi;
@@ -2864,6 +2876,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 
 	f2fs_join_shrinker(sbi);
 
+	f2fs_tuning_parameters(sbi);
+
 	f2fs_msg(sbi->sb, KERN_NOTICE, "Mounted with checkpoint version = %llx",
 				cur_cp_version(F2FS_CKPT(sbi)));
 	f2fs_update_time(sbi, CP_TIME);
-- 
2.15.0.531.g2ccb3012c9-goog