(sorter/cdc): disable block cache by default (#8982)

close #8974
pingcap · May 19, 2023 · 30ab8ae · 30ab8ae
1 parent 1fd9889
commit 30ab8ae
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Showing 4 changed files with 13 additions and 7 deletions.
diff --git a/cdc/processor/sourcemanager/engine/pebble/db.go b/cdc/processor/sourcemanager/engine/pebble/db.go
@@ -136,10 +136,14 @@ func buildPebbleOption(cfg *config.DBConfig) (opts *pebble.Options) {
 		l.IndexBlockSize = 256 << 10 // 256 KB
 		l.FilterPolicy = bloom.FilterPolicy(10)
 		l.FilterType = pebble.TableFilter
-		if i == 0 {
-			l.TargetFileSize = 8 << 20 // 8 MB
-		} else if i < 4 {
-			l.TargetFileSize = opts.Levels[i-1].TargetFileSize * 2
+		// 8M is large enough because generally Sorter won't carry too much data.
+		// Avoiding large targe file is helpful to reduce write-amplification.
+		l.TargetFileSize = 8 << 20 // 8 MB
+		switch cfg.Compression {
+		case "none":
+			l.Compression = pebble.NoCompression
+		case "snappy":
+			l.Compression = pebble.SnappyCompression
 		}
 		l.EnsureDefaults()
 	}

diff --git a/pkg/config/config_test_data.go b/pkg/config/config_test_data.go
@@ -92,7 +92,7 @@ const (
   "owner-flush-interval": 50000000,
   "processor-flush-interval": 50000000,
   "sorter": {
-    "max-memory-percentage": 10,
+    "max-memory-percentage": 0,
     "sort-dir": "/tmp/sorter",
     "max-memory-consumption": 0,
     "num-workerpool-goroutine": 0,

diff --git a/pkg/config/server_config.go b/pkg/config/server_config.go
@@ -106,7 +106,9 @@ var defaultServerConfig = &ServerConfig{
 	OwnerFlushInterval:     TomlDuration(50 * time.Millisecond),
 	ProcessorFlushInterval: TomlDuration(50 * time.Millisecond),
 	Sorter: &SorterConfig{
-		MaxMemoryPercentage: 10, // 10% is safe on machines with memory capacity <= 16GB
+		// Disable block-cache by default. TiCDC only scans events instead of
+		// accessing them randomly, so block-cache is unnecessary.
+		MaxMemoryPercentage: 0,
 		SortDir:             DefaultSortDir,
 	},
 	Security: &SecurityConfig{},

diff --git a/pkg/config/sorter.go b/pkg/config/sorter.go
@@ -38,7 +38,7 @@ type SorterConfig struct {
 
 // ValidateAndAdjust validates and adjusts the sorter configuration
 func (c *SorterConfig) ValidateAndAdjust() error {
-	if c.MaxMemoryPercentage <= 0 || c.MaxMemoryPercentage > 80 {
+	if c.MaxMemoryPercentage < 0 || c.MaxMemoryPercentage > 80 {
 		return errors.ErrIllegalSorterParameter.GenWithStackByArgs(
 			"max-memory-percentage should be a percentage and within (0, 80]")
 	}