Allow user to disable readahead by setting max-readahead smaller th…

…an blocksize (#5229) Signed-off-by: Changxin Miao <[email protected]>
juicedata · Oct 14, 2024 · c011d62 · c011d62
1 parent b4db05b
commit c011d62
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Showing 2 changed files with 2 additions and 2 deletions.
diff --git a/cmd/flags.go b/cmd/flags.go
@@ -174,7 +174,7 @@ func dataCacheFlags() []cli.Flag {
 		},
 		&cli.StringFlag{
 			Name:  "max-readahead",
-			Usage: "max buffering for read ahead in MiB",
+			Usage: "max buffering for read ahead in MiB per read session",
 		},
 		&cli.IntFlag{
 			Name:  "prefetch",

diff --git a/pkg/vfs/reader.go b/pkg/vfs/reader.go
@@ -418,7 +418,7 @@ func (f *fileReader) checkReadahead(block *frange) int {
 	seqdata := ses.total
 	readahead := ses.readahead
 	used := uint64(atomic.LoadInt64(&readBufferUsed))
-	if readahead == 0 && (block.off == 0 || seqdata > block.len) { // begin with read-ahead turned on
+	if readahead == 0 && f.r.blockSize <= f.r.readAheadMax && (block.off == 0 || seqdata > block.len) { // begin with read-ahead turned on
 		ses.readahead = f.r.blockSize
 	} else if readahead < f.r.readAheadMax && seqdata >= readahead && f.r.readAheadTotal-used > readahead*4 {
 		ses.readahead *= 2