Author: avg Date: Tue Nov 29 13:11:00 2016 New Revision: 309295 URL: https://svnweb.freebsd.org/changeset/base/309295
Log: bhyve: stability and performance improvement for dbgport The TCP server implementation in dbgport does not track clients, so it may try to write to a disconected socket resulting in SIGPIPE. Avoid that by setting SO_NOSIGPIPE socket option. Because dbgport emulates an I/O port to guest, the communication is done byte by byte. Reduce latency of the TCP/IP transfers by using TCP_NODELAY option. In my tests that change improves performance of kgdb commands with lots of output (e.g. info threads) by two orders of magnitude. A general note. Since we have a uart emulation in bhyve, that can be used for the console and gdb access to guests. So, bvmconsole and bvmdebug could be de-orbited now. But there are many existing deployments that still dependend on those. Discussed with: julian, jhb MFC after: 2 weeks Sponsored by: Panzura Modified: head/usr.sbin/bhyve/dbgport.c Modified: head/usr.sbin/bhyve/dbgport.c ============================================================================== --- head/usr.sbin/bhyve/dbgport.c Tue Nov 29 13:05:43 2016 (r309294) +++ head/usr.sbin/bhyve/dbgport.c Tue Nov 29 13:11:00 2016 (r309295) @@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$"); #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> +#include <netinet/tcp.h> #include <sys/uio.h> #include <stdio.h> @@ -55,8 +56,9 @@ static int dbg_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes, uint32_t *eax, void *arg) { - char ch; int nwritten, nread, printonce; + int on = 1; + char ch; if (bytes == 2 && in) { *eax = BVM_DBG_SIG; @@ -74,8 +76,16 @@ again: printonce = 1; } conn_fd = accept4(listen_fd, NULL, NULL, SOCK_NONBLOCK); - if (conn_fd < 0 && errno != EINTR) + if (conn_fd >= 0) { + /* Avoid EPIPE after the client drops off. */ + (void)setsockopt(conn_fd, SOL_SOCKET, SO_NOSIGPIPE, + &on, sizeof(on)); + /* Improve latency for one byte at a time tranfers. */ + (void)setsockopt(conn_fd, IPPROTO_TCP, TCP_NODELAY, + &on, sizeof(on)); + } else if (errno != EINTR) { perror("accept"); + } } if (in) { _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"