Date: Fri, 2 Dec 2016 08:21:25 +0000 (UTC) From: Julian Elischer <julian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r309401 - stable/10/usr.sbin/bhyve Message-ID: <201612020821.uB28LPJk000249@repo.freebsd.org>
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Author: julian Date: Fri Dec 2 08:21:25 2016 New Revision: 309401 URL: https://svnweb.freebsd.org/changeset/base/309401 Log: MFH: r309295 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 Sponsored by: Panzura Modified: stable/10/usr.sbin/bhyve/dbgport.c Directory Properties: stable/10/ (props changed) Modified: stable/10/usr.sbin/bhyve/dbgport.c ============================================================================== --- stable/10/usr.sbin/bhyve/dbgport.c Fri Dec 2 08:21:08 2016 (r309400) +++ stable/10/usr.sbin/bhyve/dbgport.c Fri Dec 2 08:21:25 2016 (r309401) @@ -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) {
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