stream: default hwm based on Buffer.poolSize

Slightly increase default Buffer.poolSize and make streams default
HWM correspond to Buffer.poolSize.

Author: ronag

lib/buffer.js

@@ -140,7 +140,7 @@ const constants = ObjectDefineProperties({}, {
   }
 });
 
-Buffer.poolSize = 8 * 1024;
+Buffer.poolSize = 16 * 1024;
 let poolSize, poolOffset, allocPool;
 
 const encodingsMap = ObjectCreate(null);

lib/internal/streams/state.js

@@ -4,6 +4,7 @@ const {
   MathFloor,
   NumberIsInteger,
 } = primordials;
+const { Buffer } = require('buffer');
 
 const { ERR_INVALID_ARG_VALUE } = require('internal/errors').codes;
 
@@ -13,7 +14,7 @@ function highWaterMarkFrom(options, isDuplex, duplexKey) {
 }
 
 function getDefaultHighWaterMark(objectMode) {
-  return objectMode ? 16 : 16 * 1024;
+  return objectMode ? 16 : Buffer.poolSize;
 }
 
 function getHighWaterMark(state, options, duplexKey, isDuplex) {