From a2affd7d911244da3e6b68eb191fbac7096d8faf Mon Sep 17 00:00:00 2001
From: Fangxin Lou <loufangxin@juicedata.io>
Date: Tue, 18 Feb 2025 14:42:46 +0800
Subject: [PATCH 1/2] add multi block option for random read ahead

---
 cmd/flags.go              |  4 ++++
 cmd/mount.go              |  1 +
 pkg/chunk/cached_store.go |  1 +
 pkg/vfs/reader.go         | 12 +++++++++++-
 4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/cmd/flags.go b/cmd/flags.go
index 36068af6dd17..ee6e178083d3 100644
--- a/cmd/flags.go
+++ b/cmd/flags.go
@@ -122,6 +122,10 @@ func storageFlags() []cli.Flag {
 			Value: 10,
 			Usage: "number of retries after network failure",
 		},
+		&cli.IntFlag{
+			Name:  "multi-block",
+			Usage: "number of blocks for random read ahead",
+		},
 		&cli.IntFlag{
 			Name:  "max-uploads",
 			Value: 20,
diff --git a/cmd/mount.go b/cmd/mount.go
index 68bb5936e0d7..bd4952a05176 100644
--- a/cmd/mount.go
+++ b/cmd/mount.go
@@ -339,6 +339,7 @@ func getChunkConf(c *cli.Context, format *meta.Format) *chunk.Config {
 
 		GetTimeout:    utils.Duration(c.String("get-timeout")),
 		PutTimeout:    utils.Duration(c.String("put-timeout")),
+		MultiBlock:    c.Int("multi-block"),
 		MaxUpload:     c.Int("max-uploads"),
 		MaxStageWrite: c.Int("max-stage-write"),
 		MaxRetries:    c.Int("io-retries"),
diff --git a/pkg/chunk/cached_store.go b/pkg/chunk/cached_store.go
index 70edac800bb5..c4d7cfc01c21 100644
--- a/pkg/chunk/cached_store.go
+++ b/pkg/chunk/cached_store.go
@@ -561,6 +561,7 @@ type Config struct {
 	FreeSpace         float32
 	AutoCreate        bool
 	Compress          string
+	MultiBlock	  int
 	MaxUpload         int
 	MaxStageWrite     int
 	MaxRetries        int
diff --git a/pkg/vfs/reader.go b/pkg/vfs/reader.go
index e8a858b50f1a..9de991c3da9b 100644
--- a/pkg/vfs/reader.go
+++ b/pkg/vfs/reader.go
@@ -365,11 +365,19 @@ func (f *fileReader) release() {
 	}
 }
 
+func (f *fileReader) readMargin(ahead, blklen uint64) uint64 {
+	if f.r.multiBlock == 0 ||
+	   blklen * f.r.multiBlock > ahead + f.r.blockSize {
+		return ahead + f.r.blockSize
+	}
+	return blklen * f.r.multiBlock
+}
+
 func (f *fileReader) guessSession(block *frange) int {
 	idx := -1
 	var closestOff uint64
 	for i, ses := range f.sessions {
-		if ses.lastOffset > closestOff && ses.lastOffset <= block.off && block.off <= ses.lastOffset+ses.readahead+f.r.blockSize {
+		if ses.lastOffset > closestOff && ses.lastOffset <= block.off && block.off <= ses.lastOffset+f.readMargin(ses.readahead, block.len) {
 			idx = i
 			closestOff = ses.lastOffset
 		}
@@ -694,6 +702,7 @@ type dataReader struct {
 	m              meta.Meta
 	store          chunk.ChunkStore
 	files          map[Ino]*fileReader
+	multiBlock     uint64
 	blockSize      uint64
 	bufferSize     int64
 	readAheadMax   uint64
@@ -715,6 +724,7 @@ func NewDataReader(conf *Config, m meta.Meta, store chunk.ChunkStore) DataReader
 		m:              m,
 		store:          store,
 		files:          make(map[Ino]*fileReader),
+		multiBlock:	uint64(conf.Chunk.MultiBlock),
 		blockSize:      uint64(conf.Chunk.BlockSize),
 		bufferSize:     int64(conf.Chunk.BufferSize),
 		readAheadTotal: uint64(readAheadTotal),

From 9685e12a62b455e5a55c23210632ce27083fab8f Mon Sep 17 00:00:00 2001
From: Fangxin Lou <loufangxin@juicedata.io>
Date: Tue, 18 Feb 2025 15:25:22 +0800
Subject: [PATCH 2/2] move option to cache category

---
 cmd/flags.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/cmd/flags.go b/cmd/flags.go
index ee6e178083d3..64c04d14cda9 100644
--- a/cmd/flags.go
+++ b/cmd/flags.go
@@ -122,10 +122,6 @@ func storageFlags() []cli.Flag {
 			Value: 10,
 			Usage: "number of retries after network failure",
 		},
-		&cli.IntFlag{
-			Name:  "multi-block",
-			Usage: "number of blocks for random read ahead",
-		},
 		&cli.IntFlag{
 			Name:  "max-uploads",
 			Value: 20,
@@ -185,6 +181,10 @@ func dataCacheFlags() []cli.Flag {
 			Name:  "max-readahead",
 			Usage: "max buffering for read ahead in MiB per read session",
 		},
+                &cli.IntFlag{
+                        Name:  "multi-block",
+                        Usage: "number of blocks for random read ahead",
+                },
 		&cli.IntFlag{
 			Name:  "prefetch",
 			Value: 1,