Date: Tue, 23 Oct 2012 14:19:45 +0000 (UTC) From: Andre Oppermann <andre@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r241931 - in head/sys: conf kern Message-ID: <201210231419.q9NEJjYH082863@svn.freebsd.org>
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Author: andre Date: Tue Oct 23 14:19:44 2012 New Revision: 241931 URL: http://svn.freebsd.org/changeset/base/241931 Log: Replace the ill-named ZERO_COPY_SOCKET kernel option with two more appropriate named kernel options for the very distinct send and receive path. "options SOCKET_SEND_COW" enables VM page copy-on-write based sending of data on an outbound socket. NB: The COW based send mechanism is not safe and may result in kernel crashes. "options SOCKET_RECV_PFLIP" enables VM kernel/userspace page flipping for special disposable pages attached as external storage to mbufs. Only the naming of the kernel options is changed and their corresponding #ifdef sections are adjusted. No functionality is added or removed. Discussed with: alc (mechanism and limitations of send side COW) Modified: head/sys/conf/NOTES head/sys/conf/options head/sys/kern/subr_uio.c head/sys/kern/uipc_socket.c Modified: head/sys/conf/NOTES ============================================================================== --- head/sys/conf/NOTES Tue Oct 23 12:39:17 2012 (r241930) +++ head/sys/conf/NOTES Tue Oct 23 14:19:44 2012 (r241931) @@ -964,12 +964,20 @@ options TCP_SIGNATURE #include support # a smooth scheduling of the traffic. options DUMMYNET -# Zero copy sockets support. This enables "zero copy" for sending and -# receiving data via a socket. The send side works for any type of NIC, -# the receive side only works for NICs that support MTUs greater than the -# page size of your architecture and that support header splitting. See -# zero_copy(9) for more details. -options ZERO_COPY_SOCKETS +# "Zero copy" sockets support is split into the send and receive path +# which operate very differently. +# For the send path the VM page with the data is wired into the kernel +# and marked as COW (copy-on-write). If the application touches the +# data while it is still in the send socket buffer the page is copied +# and divorced from its kernel wiring (no longer zero copy). +# The receive side requires explicit NIC driver support to create +# disposable pages which are flipped from kernel to user-space VM. +# See zero_copy(9) for more details. +# XXX: The COW based send mechanism is not safe and may result in +# kernel crashes. +# XXX: None of the current NIC drivers support disposeable pages. +options SOCKET_SEND_COW +options SOCKET_RECV_PFLIP ##################################################################### # FILESYSTEM OPTIONS Modified: head/sys/conf/options ============================================================================== --- head/sys/conf/options Tue Oct 23 12:39:17 2012 (r241930) +++ head/sys/conf/options Tue Oct 23 14:19:44 2012 (r241931) @@ -520,7 +520,8 @@ NGATM_CCATM opt_netgraph.h # DRM options DRM_DEBUG opt_drm.h -ZERO_COPY_SOCKETS opt_zero.h +SOCKET_SEND_COW opt_zero.h +SOCKET_RECV_PFLIP opt_zero.h TI_SF_BUF_JUMBO opt_ti.h TI_JUMBO_HDRSPLIT opt_ti.h BCE_JUMBO_HDRSPLIT opt_bce.h Modified: head/sys/kern/subr_uio.c ============================================================================== --- head/sys/kern/subr_uio.c Tue Oct 23 12:39:17 2012 (r241930) +++ head/sys/kern/subr_uio.c Tue Oct 23 14:19:44 2012 (r241931) @@ -57,7 +57,7 @@ __FBSDID("$FreeBSD$"); #include <vm/vm_extern.h> #include <vm/vm_page.h> #include <vm/vm_map.h> -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_SEND_COW #include <vm/vm_object.h> #endif @@ -66,7 +66,7 @@ SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, static int uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault); -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_SEND_COW /* Declared in uipc_socket.c */ extern int so_zero_copy_receive; @@ -128,7 +128,7 @@ retry: vm_map_lookup_done(map, entry); return(KERN_SUCCESS); } -#endif /* ZERO_COPY_SOCKETS */ +#endif /* SOCKET_SEND_COW */ int copyin_nofault(const void *udaddr, void *kaddr, size_t len) @@ -261,7 +261,7 @@ uiomove_frombuf(void *buf, int buflen, s return (uiomove((char *)buf + offset, n, uio)); } -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_RECV_PFLIP /* * Experimental support for zero-copy I/O */ @@ -356,7 +356,7 @@ uiomoveco(void *cp, int n, struct uio *u } return (0); } -#endif /* ZERO_COPY_SOCKETS */ +#endif /* SOCKET_RECV_PFLIP */ /* * Give next character to user as result of read. Modified: head/sys/kern/uipc_socket.c ============================================================================== --- head/sys/kern/uipc_socket.c Tue Oct 23 12:39:17 2012 (r241930) +++ head/sys/kern/uipc_socket.c Tue Oct 23 14:19:44 2012 (r241931) @@ -219,17 +219,20 @@ static int numopensockets; SYSCTL_INT(_kern_ipc, OID_AUTO, numopensockets, CTLFLAG_RD, &numopensockets, 0, "Number of open sockets"); -#ifdef ZERO_COPY_SOCKETS -/* These aren't static because they're used in other files. */ -int so_zero_copy_send = 1; -int so_zero_copy_receive = 1; +#if defined(SOCKET_SEND_COW) || defined(SOCKET_RECV_PFLIP) SYSCTL_NODE(_kern_ipc, OID_AUTO, zero_copy, CTLFLAG_RD, 0, "Zero copy controls"); +#ifdef SOCKET_RECV_PFLIP +int so_zero_copy_receive = 1; SYSCTL_INT(_kern_ipc_zero_copy, OID_AUTO, receive, CTLFLAG_RW, &so_zero_copy_receive, 0, "Enable zero copy receive"); +#endif +#ifdef SOCKET_SEND_COW +int so_zero_copy_send = 1; SYSCTL_INT(_kern_ipc_zero_copy, OID_AUTO, send, CTLFLAG_RW, &so_zero_copy_send, 0, "Enable zero copy send"); -#endif /* ZERO_COPY_SOCKETS */ +#endif /* SOCKET_SEND_COW */ +#endif /* SOCKET_SEND_COW || SOCKET_RECV_PFLIP */ /* * accept_mtx locks down per-socket fields relating to accept queues. See @@ -903,7 +906,7 @@ sodisconnect(struct socket *so) return (error); } -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_SEND_COW struct so_zerocopy_stats{ int size_ok; int align_ok; @@ -1008,7 +1011,7 @@ out: *retmp = top; return (error); } -#endif /* ZERO_COPY_SOCKETS */ +#endif /* SOCKET_SEND_COW */ #define SBLOCKWAIT(f) (((f) & MSG_DONTWAIT) ? 0 : SBL_WAIT) @@ -1019,7 +1022,7 @@ sosend_dgram(struct socket *so, struct s long space; ssize_t resid; int clen = 0, error, dontroute; -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_SEND_COW int atomic = sosendallatonce(so) || top; #endif @@ -1104,7 +1107,7 @@ sosend_dgram(struct socket *so, struct s if (flags & MSG_EOR) top->m_flags |= M_EOR; } else { -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_SEND_COW error = sosend_copyin(uio, &top, atomic, &space, flags); if (error) goto out; @@ -1121,7 +1124,7 @@ sosend_dgram(struct socket *so, struct s goto out; } space -= resid - uio->uio_resid; -#endif +#endif /* SOCKET_SEND_COW */ resid = uio->uio_resid; } KASSERT(resid == 0, ("sosend_dgram: resid != 0")); @@ -1293,7 +1296,7 @@ restart: if (flags & MSG_EOR) top->m_flags |= M_EOR; } else { -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_SEND_COW error = sosend_copyin(uio, &top, atomic, &space, flags); if (error != 0) @@ -1313,7 +1316,7 @@ restart: goto release; } space -= resid - uio->uio_resid; -#endif +#endif /* SOCKET_SEND_COW */ resid = uio->uio_resid; } if (dontroute) { @@ -1405,7 +1408,7 @@ soreceive_rcvoob(struct socket *so, stru if (error) goto bad; do { -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_RECV_PFLIP if (so_zero_copy_receive) { int disposable; @@ -1419,7 +1422,7 @@ soreceive_rcvoob(struct socket *so, stru min(uio->uio_resid, m->m_len), uio, disposable); } else -#endif /* ZERO_COPY_SOCKETS */ +#endif /* SOCKET_RECV_PFLIP */ error = uiomove(mtod(m, void *), (int) min(uio->uio_resid, m->m_len), uio); m = m_free(m); @@ -1743,7 +1746,7 @@ dontblock: SBLASTRECORDCHK(&so->so_rcv); SBLASTMBUFCHK(&so->so_rcv); SOCKBUF_UNLOCK(&so->so_rcv); -#ifdef ZERO_COPY_SOCKETS +#ifdef SOCKET_RECV_PFLIP if (so_zero_copy_receive) { int disposable; @@ -1757,7 +1760,7 @@ dontblock: (int)len, uio, disposable); } else -#endif /* ZERO_COPY_SOCKETS */ +#endif /* SOCKET_RECV_PFLIP */ error = uiomove(mtod(m, char *) + moff, (int)len, uio); SOCKBUF_LOCK(&so->so_rcv); if (error) {
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