fix misspell (#1592)

diff --git a/picker_wrapper_test.go b/picker_wrapper_test.go
index 23bc8f2..37dffa9 100644
--- a/picker_wrapper_test.go
+++ b/picker_wrapper_test.go
@@ -100,7 +100,7 @@
 	bp := newPickerWrapper()
 	var finishedCount uint64
 	bp.updatePicker(&testingPicker{err: balancer.ErrNoSubConnAvailable, maxCalled: goroutineCount})
-	// All goroutines should block because picker returns no sc avilable.
+	// All goroutines should block because picker returns no sc available.
 	for i := goroutineCount; i > 0; i-- {
 		go func() {
 			if tr, _, err := bp.pick(context.Background(), true, balancer.PickOptions{}); err != nil || tr != testT {
diff --git a/transport/http2_client.go b/transport/http2_client.go
index 6ca6cc6..71731a6 100644
--- a/transport/http2_client.go
+++ b/transport/http2_client.go
@@ -417,7 +417,7 @@
 	if sq > 1 {
 		t.streamsQuota.add(sq - 1)
 	}
-	// TODO(mmukhi): Benchmark if the perfomance gets better if count the metadata and other header fields
+	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
 	// first and create a slice of that exact size.
 	// Make the slice of certain predictable size to reduce allocations made by append.
 	hfLen := 7 // :method, :scheme, :path, :authority, content-type, user-agent, te
diff --git a/transport/http2_server.go b/transport/http2_server.go
index bad29b8..f84d70a 100644
--- a/transport/http2_server.go
+++ b/transport/http2_server.go
@@ -708,7 +708,7 @@
 	}
 	md = s.header
 	s.mu.Unlock()
-	// TODO(mmukhi): Benchmark if the perfomance gets better if count the metadata and other header fields
+	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
 	// first and create a slice of that exact size.
 	headerFields := make([]hpack.HeaderField, 0, 2) // at least :status, content-type will be there if none else.
 	headerFields = append(headerFields, hpack.HeaderField{Name: ":status", Value: "200"})
@@ -769,7 +769,7 @@
 		headersSent = true
 	}
 
-	// TODO(mmukhi): Benchmark if the perfomance gets better if count the metadata and other header fields
+	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
 	// first and create a slice of that exact size.
 	headerFields := make([]hpack.HeaderField, 0, 2) // grpc-status and grpc-message will be there if none else.
 	if !headersSent {