Increase rioConnsetWrite max chunk size to 16K

src/rio.c

@@ -528,7 +528,7 @@ static size_t rioConnsetWrite(rio *r, const void *buf, size_t len) {
      * parallelize while the kernel is sending data in background to
      * the TCP socket. */
     while (len) {
-        size_t count = len < 1024 ? len : 1024;
+        size_t count = len < RIO_WRITE_MAX_CHUNK_SIZE ? len : RIO_WRITE_MAX_CHUNK_SIZE;
         int broken = 0;
         for (j = 0; j < r->io.connset.numconns; j++) {
             if (r->io.connset.state[j] != 0) {

src/server.h

@@ -167,6 +167,11 @@ struct hdr_histogram;
  * and hold back additional reading based on this factor. */
 #define CHILD_COW_DUTY_CYCLE 100
 
+/* When child process is performing write to connset it iterates on the set
+ * writing a chunk of the available data to send on each connection.
+ * This constant defines the maximal size of the chunk to use. */
+#define RIO_CONNSET_WRITE_MAX_CHUNK_SIZE 16384
+
 /* Instantaneous metrics tracking. */
 #define STATS_METRIC_SAMPLES 16               /* Number of samples per metric. */
 #define STATS_METRIC_COMMAND 0                /* Number of commands executed. */