replace io.Discard usage to fix some NUMA copy() latencies (#18394)

replace io.Discard usage to fix NUMA copy() latencies

On NUMA systems copying from 8K buffer allocated via
io.Discard leads to large latency build-up for every

```
copy(new8kbuf, largebuf)
```

can in-cur upto 1ms worth of latencies on NUMA systems
due to memory sharding across NUMA nodes.

cmd/admin-handlers-site-replication.go

@@ -31,6 +31,7 @@ import (
 
 	"github.com/dustin/go-humanize"
 	"github.com/minio/madmin-go/v3"
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 	"github.com/minio/mux"
 	"github.com/minio/pkg/v2/policy"
@@ -537,7 +538,7 @@ func (a adminAPIHandlers) SiteReplicationDevNull(w http.ResponseWriter, r *http.
 
 	connectTime := time.Now()
 	for {
-		n, err := io.CopyN(io.Discard, r.Body, 128*humanize.KiByte)
+		n, err := io.CopyN(xioutil.Discard, r.Body, 128*humanize.KiByte)
 		atomic.AddUint64(&globalSiteNetPerfRX.RX, uint64(n))
 		if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
 			// If there is a disconnection before globalNetPerfMinDuration (we give a margin of error of 1 sec)

cmd/admin-handlers.go

@@ -52,6 +52,7 @@ import (
 	"github.com/minio/minio/internal/dsync"
 	"github.com/minio/minio/internal/handlers"
 	xhttp "github.com/minio/minio/internal/http"
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/kms"
 	"github.com/minio/minio/internal/logger"
 	"github.com/minio/mux"
@@ -756,11 +757,8 @@ func (a adminAPIHandlers) ProfileHandler(w http.ResponseWriter, r *http.Request)
 			return
 		}
 	}
-	// read request body
-	io.CopyN(io.Discard, r.Body, 1)
 
 	globalProfilerMu.Lock()
-
 	if globalProfiler == nil {
 		globalProfiler = make(map[string]minioProfiler, 10)
 	}
@@ -1220,7 +1218,7 @@ func (a adminAPIHandlers) ClientDevNull(w http.ResponseWriter, r *http.Request)
 	totalRx := int64(0)
 	connectTime := time.Now()
 	for {
-		n, err := io.CopyN(io.Discard, r.Body, 128*humanize.KiByte)
+		n, err := io.CopyN(xioutil.Discard, r.Body, 128*humanize.KiByte)
 		if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
 			// would mean the network is not stable. Logging here will help in debugging network issues.
 			if time.Since(connectTime) < (globalNetPerfMinDuration - time.Second) {

cmd/erasure-utils.go

@@ -18,7 +18,6 @@
 package cmd
 
 import (
-	"bytes"
 	"context"
 	"encoding/base64"
 	"fmt"
@@ -26,7 +25,6 @@ import (
 	"strings"
 
 	"github.com/klauspost/reedsolomon"
-	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 )
 
@@ -85,7 +83,7 @@ func writeDataBlocks(ctx context.Context, dst io.Writer, enBlocks [][]byte, data
 
 		// We have written all the blocks, write the last remaining block.
 		if write < int64(len(block)) {
-			n, err := xioutil.Copy(dst, bytes.NewReader(block[:write]))
+			n, err := dst.Write(block[:write])
 			if err != nil {
 				// The writer will be closed incase of range queries, which will emit ErrClosedPipe.
 				// The reader pipe might be closed at ListObjects io.EOF ignore it.
@@ -94,12 +92,12 @@ func writeDataBlocks(ctx context.Context, dst io.Writer, enBlocks [][]byte, data
 				}
 				return 0, err
 			}
-			totalWritten += n
+			totalWritten += int64(n)
 			break
 		}
 
 		// Copy the block.
-		n, err := xioutil.Copy(dst, bytes.NewReader(block))
+		n, err := dst.Write(block)
 		if err != nil {
 			// The writer will be closed incase of range queries, which will emit ErrClosedPipe.
 			// The reader pipe might be closed at ListObjects io.EOF ignore it.
@@ -110,10 +108,10 @@ func writeDataBlocks(ctx context.Context, dst io.Writer, enBlocks [][]byte, data
 		}
 
 		// Decrement output size.
-		write -= n
+		write -= int64(n)
 
 		// Increment written.
-		totalWritten += n
+		totalWritten += int64(n)
 	}
 
 	// Success.

cmd/peer-rest-server.go

@@ -33,6 +33,7 @@ import (
 	"github.com/minio/madmin-go/v3"
 	b "github.com/minio/minio/internal/bucket/bandwidth"
 	"github.com/minio/minio/internal/event"
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 	"github.com/minio/minio/internal/pubsub"
 	"github.com/minio/mux"
@@ -1423,7 +1424,7 @@ func (s *peerRESTServer) DevNull(w http.ResponseWriter, r *http.Request) {
 	connectTime := time.Now()
 	ctx := newContext(r, w, "DevNull")
 	for {
-		n, err := io.CopyN(io.Discard, r.Body, 128*humanize.KiByte)
+		n, err := io.CopyN(xioutil.Discard, r.Body, 128*humanize.KiByte)
 		atomic.AddUint64(&globalNetPerfRX.RX, uint64(n))
 		if err != nil && err != io.EOF {
 			// If there is a disconnection before globalNetPerfMinDuration (we give a margin of error of 1 sec)

cmd/perf-tests.go

@@ -34,6 +34,7 @@ import (
 	"github.com/minio/madmin-go/v3"
 	"github.com/minio/minio-go/v7"
 	xhttp "github.com/minio/minio/internal/http"
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/pkg/v2/randreader"
 )
 
@@ -148,6 +149,8 @@ func selfSpeedTest(ctx context.Context, opts speedTestOpts) (SpeedTestResult, er
 	var downloadTimes madmin.TimeDurations
 	var downloadTTFB madmin.TimeDurations
 	wg.Add(opts.concurrency)
+
+	c := minio.Core{Client: globalMinioClient}
 	for i := 0; i < opts.concurrency; i++ {
 		go func(i int) {
 			defer wg.Done()
@@ -161,7 +164,8 @@ func selfSpeedTest(ctx context.Context, opts speedTestOpts) (SpeedTestResult, er
 				}
 				tmpObjName := pathJoin(objNamePrefix, fmt.Sprintf("%d/%d", i, j))
 				t := time.Now()
-				r, err := globalMinioClient.GetObject(downloadsCtx, opts.bucketName, tmpObjName, gopts)
+
+				r, _, _, err := c.GetObject(downloadsCtx, opts.bucketName, tmpObjName, gopts)
 				if err != nil {
 					errResp, ok := err.(minio.ErrorResponse)
 					if ok && errResp.StatusCode == http.StatusNotFound {
@@ -178,7 +182,7 @@ func selfSpeedTest(ctx context.Context, opts speedTestOpts) (SpeedTestResult, er
 				fbr := firstByteRecorder{
 					r: r,
 				}
-				n, err := io.Copy(io.Discard, &fbr)
+				n, err := xioutil.Copy(xioutil.Discard, &fbr)
 				r.Close()
 				if err == nil {
 					response := time.Since(t)

cmd/storage-rest-client.go

@@ -856,10 +856,7 @@ func (client *storageRESTClient) CleanAbandonedData(ctx context.Context, volume
 		return err
 	}
 	defer xhttp.DrainBody(respBody)
-	respReader, err := waitForHTTPResponse(respBody)
-	if err == nil {
-		io.Copy(io.Discard, respReader)
-	}
+	_, err = waitForHTTPResponse(respBody)
 	return err
 }