diff --git a/br/pkg/lightning/backend/external/BUILD.bazel b/br/pkg/lightning/backend/external/BUILD.bazel
index 2bc61430fb881..999b8460fd9e3 100644
--- a/br/pkg/lightning/backend/external/BUILD.bazel
+++ b/br/pkg/lightning/backend/external/BUILD.bazel
@@ -35,6 +35,7 @@ go_library(
         "//pkg/util/mathutil",
         "//pkg/util/size",
         "@com_github_cockroachdb_pebble//:pebble",
+        "@com_github_docker_go_units//:go-units",
         "@com_github_jfcg_sorty_v2//:sorty",
         "@com_github_pingcap_errors//:errors",
         "@org_golang_x_sync//errgroup",
diff --git a/br/pkg/lightning/backend/external/writer.go b/br/pkg/lightning/backend/external/writer.go
index b651e01b19c59..9612e8a3d11f5 100644
--- a/br/pkg/lightning/backend/external/writer.go
+++ b/br/pkg/lightning/backend/external/writer.go
@@ -19,10 +19,12 @@ import (
 	"context"
 	"encoding/hex"
 	"path/filepath"
+	"slices"
 	"strconv"
 	"sync"
 	"time"
 
+	"github.com/docker/go-units"
 	"github.com/jfcg/sorty/v2"
 	"github.com/pingcap/errors"
 	"github.com/pingcap/tidb/br/pkg/lightning/backend"
@@ -385,12 +387,25 @@ func (w *Writer) flushKVs(ctx context.Context, fromClose bool) (err error) {
 		return err
 	}
 
-	ts := time.Now()
-	savedBytes := w.batchSize
-
+	var (
+		savedBytes                  uint64
+		statSize                    int
+		sortDuration, writeDuration time.Duration
+		writeStartTime              time.Time
+	)
+	savedBytes = w.batchSize
 	startTs := time.Now()
-	var startTsForWrite time.Time
 
+	getSpeed := func(n uint64, dur float64, isBytes bool) string {
+		if dur == 0 {
+			return "-"
+		}
+		if isBytes {
+			return units.BytesSize(float64(n) / dur)
+		}
+		return units.HumanSize(float64(n) / dur)
+	}
+	kvCnt := len(w.writeBatch)
 	defer func() {
 		w.currentSeq++
 		err1, err2 := dataWriter.Close(ctx), statWriter.Close(ctx)
@@ -407,31 +422,45 @@ func (w *Writer) flushKVs(ctx context.Context, fromClose bool) (err error) {
 			err = err2
 			return
 		}
+		writeDuration = time.Since(writeStartTime)
 		logger.Info("flush kv",
-			zap.Duration("time", time.Since(ts)),
 			zap.Uint64("bytes", savedBytes),
-			zap.Any("rate", float64(savedBytes)/1024.0/1024.0/time.Since(ts).Seconds()))
-		metrics.GlobalSortWriteToCloudStorageDuration.WithLabelValues("write").Observe(time.Since(startTsForWrite).Seconds())
-		metrics.GlobalSortWriteToCloudStorageRate.WithLabelValues("write").Observe(float64(savedBytes) / 1024.0 / 1024.0 / time.Since(startTsForWrite).Seconds())
+			zap.Int("kv-cnt", kvCnt),
+			zap.Int("stat-size", statSize),
+			zap.Duration("sort-time", sortDuration),
+			zap.Duration("write-time", writeDuration),
+			zap.String("sort-speed(kv/s)", getSpeed(uint64(kvCnt), sortDuration.Seconds(), false)),
+			zap.String("write-speed(bytes/s)", getSpeed(savedBytes, writeDuration.Seconds(), true)),
+			zap.String("writer-id", w.writerID),
+		)
+		metrics.GlobalSortWriteToCloudStorageDuration.WithLabelValues("write").Observe(writeDuration.Seconds())
+		metrics.GlobalSortWriteToCloudStorageRate.WithLabelValues("write").Observe(float64(savedBytes) / 1024.0 / 1024.0 / writeDuration.Seconds())
 		metrics.GlobalSortWriteToCloudStorageDuration.WithLabelValues("sort_and_write").Observe(time.Since(startTs).Seconds())
 		metrics.GlobalSortWriteToCloudStorageRate.WithLabelValues("sort_and_write").Observe(float64(savedBytes) / 1024.0 / 1024.0 / time.Since(startTs).Seconds())
 	}()
 
-	sorty.MaxGor = min(8, uint64(variable.GetDDLReorgWorkerCounter()))
-	sorty.Sort(len(w.writeBatch), func(i, j, r, s int) bool {
-		if bytes.Compare(w.writeBatch[i].Key, w.writeBatch[j].Key) < 0 {
-			if r != s {
-				w.writeBatch[r], w.writeBatch[s] = w.writeBatch[s], w.writeBatch[r]
+	sortStart := time.Now()
+	if w.shareMu != nil {
+		sorty.MaxGor = min(8, uint64(variable.GetDDLReorgWorkerCounter()))
+		sorty.Sort(len(w.writeBatch), func(i, j, r, s int) bool {
+			if bytes.Compare(w.writeBatch[i].Key, w.writeBatch[j].Key) < 0 {
+				if r != s {
+					w.writeBatch[r], w.writeBatch[s] = w.writeBatch[s], w.writeBatch[r]
+				}
+				return true
 			}
-			return true
-		}
-		return false
-	})
-
-	startTsForWrite = time.Now()
-	metrics.GlobalSortWriteToCloudStorageDuration.WithLabelValues("sort").Observe(time.Since(startTs).Seconds())
-	metrics.GlobalSortWriteToCloudStorageRate.WithLabelValues("sort").Observe(float64(savedBytes) / 1024.0 / 1024.0 / time.Since(startTs).Seconds())
+			return false
+		})
+	} else {
+		slices.SortFunc(w.writeBatch[:], func(i, j common.KvPair) int {
+			return bytes.Compare(i.Key, j.Key)
+		})
+	}
+	sortDuration = time.Since(sortStart)
 
+	writeStartTime = time.Now()
+	metrics.GlobalSortWriteToCloudStorageDuration.WithLabelValues("sort").Observe(sortDuration.Seconds())
+	metrics.GlobalSortWriteToCloudStorageRate.WithLabelValues("sort").Observe(float64(savedBytes) / 1024.0 / 1024.0 / sortDuration.Seconds())
 	w.kvStore, err = NewKeyValueStore(ctx, dataWriter, w.rc)
 	if err != nil {
 		return err
@@ -447,7 +476,9 @@ func (w *Writer) flushKVs(ctx context.Context, fromClose bool) (err error) {
 	}
 
 	w.kvStore.Close()
-	_, err = statWriter.Write(ctx, w.rc.encode())
+	encodedStat := w.rc.encode()
+	statSize = len(encodedStat)
+	_, err = statWriter.Write(ctx, encodedStat)
 	if err != nil {
 		return err
 	}
@@ -474,7 +505,6 @@ func (w *Writer) flushKVs(ctx context.Context, fromClose bool) (err error) {
 	w.writeBatch = w.writeBatch[:0]
 	w.rc.reset()
 	w.kvBuffer.Reset()
-	savedBytes = w.batchSize
 	w.batchSize = 0
 	return nil
 }
diff --git a/pkg/disttask/importinto/encode_and_sort_operator.go b/pkg/disttask/importinto/encode_and_sort_operator.go
index 8d5b36e93d613..2a74a45821920 100644
--- a/pkg/disttask/importinto/encode_and_sort_operator.go
+++ b/pkg/disttask/importinto/encode_and_sort_operator.go
@@ -158,7 +158,7 @@ func newChunkWorker(ctx context.Context, op *encodeAndSortOperator, indexMemoryS
 			builder := external.NewWriterBuilder().
 				SetOnCloseFunc(func(summary *external.WriterSummary) {
 					op.sharedVars.mergeIndexSummary(indexID, summary)
-				}).SetMemorySizeLimit(indexMemorySizeLimit).SetMutex(&op.sharedVars.ShareMu)
+				}).SetMemorySizeLimit(indexMemorySizeLimit)
 			prefix := subtaskPrefix(op.taskID, op.subtaskID)
 			// writer id for index: index/{indexID}/{workerID}
 			writerID := path.Join("index", strconv.Itoa(int(indexID)), workerUUID)
@@ -168,7 +168,7 @@ func newChunkWorker(ctx context.Context, op *encodeAndSortOperator, indexMemoryS
 
 		// sorted data kv storage path: /{taskID}/{subtaskID}/data/{workerID}
 		builder := external.NewWriterBuilder().
-			SetOnCloseFunc(op.sharedVars.mergeDataSummary).SetMutex(&op.sharedVars.ShareMu)
+			SetOnCloseFunc(op.sharedVars.mergeDataSummary)
 		prefix := subtaskPrefix(op.taskID, op.subtaskID)
 		// writer id for data: data/{workerID}
 		writerID := path.Join("data", workerUUID)