Date: Tue, 26 Nov 2013 12:00:56 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r258645 - projects/sendfile/sys/kern Message-ID: <201311261200.rAQC0uwB048012@svn.freebsd.org>
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Author: glebius Date: Tue Nov 26 12:00:56 2013 New Revision: 258645 URL: http://svnweb.freebsd.org/changeset/base/258645 Log: Remove two mbuf chain traversals from sendfile(). The first one is a short traversal of of headers chain done in m_last(), and the second one is m_length() done right before the socket write. To achieve this, store header mbuf in *mh and its tail in *mhtail. Stack the *mh and *m out of the inner loop, before the socket write. While here, simplify the headers handling block of code. Sponsored by: Netflix Sponsored by: Nginx, Inc. Modified: projects/sendfile/sys/kern/uipc_syscalls.c Modified: projects/sendfile/sys/kern/uipc_syscalls.c ============================================================================== --- projects/sendfile/sys/kern/uipc_syscalls.c Tue Nov 26 11:13:24 2013 (r258644) +++ projects/sendfile/sys/kern/uipc_syscalls.c Tue Nov 26 12:00:56 2013 (r258645) @@ -2206,7 +2206,7 @@ vn_sendfile(struct file *fp, int sockfd, struct vnode *vp; struct vm_object *obj; struct socket *so; - struct mbuf *m; + struct mbuf *m, *mh, *mhtail; struct sf_buf *sf; struct vm_page *pg; struct shmfd *shmfd; @@ -2222,7 +2222,7 @@ vn_sendfile(struct file *fp, int sockfd, m = NULL; sfs = NULL; fsbytes = sbytes = 0; - hdrlen = mnw = 0; + mnw = 0; rem = nbytes; obj_size = 0; inflight_called = false; @@ -2258,29 +2258,29 @@ vn_sendfile(struct file *fp, int sockfd, #endif /* If headers are specified copy them into mbufs. */ - if (hdr_uio != NULL) { + if (hdr_uio != NULL && hdr_uio->uio_resid > 0) { hdr_uio->uio_td = td; hdr_uio->uio_rw = UIO_WRITE; - if (hdr_uio->uio_resid > 0) { - /* - * In FBSD < 5.0 the nbytes to send also included - * the header. If compat is specified subtract the - * header size from nbytes. - */ - if (kflags & SFK_COMPAT) { - if (nbytes > hdr_uio->uio_resid) - nbytes -= hdr_uio->uio_resid; - else - nbytes = 0; - } - m = m_uiotombuf(hdr_uio, (mnw ? M_NOWAIT : M_WAITOK), - 0, 0, 0); - if (m == NULL) { - error = mnw ? EAGAIN : ENOBUFS; - goto out; - } - hdrlen = m_length(m, NULL); + /* + * In FBSD < 5.0 the nbytes to send also included + * the header. If compat is specified subtract the + * header size from nbytes. + */ + if (kflags & SFK_COMPAT) { + if (nbytes > hdr_uio->uio_resid) + nbytes -= hdr_uio->uio_resid; + else + nbytes = 0; + } + mh = m_uiotombuf(hdr_uio, (mnw ? M_NOWAIT : M_WAITOK), 0, 0, 0); + if (mh == NULL) { + error = mnw ? EAGAIN : ENOBUFS; + goto out; } + hdrlen = m_length(mh, &mhtail); + } else { + mh = NULL; + hdrlen = 0; } /* @@ -2485,8 +2485,6 @@ retry_space: /* Append to mbuf chain. */ if (mtail != NULL) mtail->m_next = m0; - else if (m != NULL) - m_last(m)->m_next = m0; else m = m0; mtail = m0; @@ -2505,11 +2503,20 @@ retry_space: if (vp != NULL) VOP_UNLOCK(vp, 0); + /* Prepend header, if any. */ + if (hdrlen) { + mhtail->m_next = m; + m = mh; + } + /* Add the buffer chain to the socket buffer. */ - if (m != NULL) { - int mlen, err; + if (loopbytes + hdrlen > 0) { + int err; + + KASSERT(m_length(m, NULL) == loopbytes + hdrlen, + ("%s: mlen %u loop %d hdr %d", __func__, + m_length(m, NULL), loopbytes, hdrlen)); - mlen = m_length(m, NULL); SOCKBUF_LOCK(&so->so_snd); if (so->so_snd.sb_state & SBS_CANTSENDMORE) { error = EPIPE; @@ -2532,12 +2539,10 @@ retry_space: * - fsbytes contains the total amount * of bytes sent from the file. */ - sbytes += mlen; - fsbytes += mlen; - if (hdrlen) { - fsbytes -= hdrlen; + sbytes += loopbytes + hdrlen; + fsbytes += loopbytes; + if (hdrlen) hdrlen = 0; - } } else if (error == 0) error = err; m = NULL; /* pru_send always consumes */
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