[SR-Users] how to enable tcp_write_buf?

I tried to issue mtree.list command using xmlrpc query that would result in large response, and got error Aug 15 18:12:07 char /usr/bin/sip-proxy[10348]: ERROR: <core> [core/tcp_main.c:618]: _wbufq_add(): (221375 bytes): write queue full or timeout (0, total 0, last write 55534052 s ago) Aug 15 18:12:07 char /usr/bin/sip-proxy[10348]: ERROR: xmlrpc [xmlrpc.c:811]: send_reply(): Error while sending reply Aug 15 18:12:07 char /usr/bin/sip-proxy[10367]: ERROR: <core> [core/tcp_main.c:3551]: handle_ser_child(): received CON_ERROR for 0x7f112ad22be0 (id 5), refcnt 3, flags 0x4018 I though that perhaps I could get rid of the error by increasing value of core var tcp_conn_wq_max. Description of the var tells: Maximum bytes queued for write allowed per connection. Attempting to queue more bytes would result in an error and in the connection being closed (too slow). If tcp_write_buf is not enabled, it has no effect. What is tcp_write_buf and how to enable it? I could not find anything about it in core cookbook. -- Juha