From patchwork Fri Feb 1 13:53:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 217460 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 078FE2C0293 for ; Sat, 2 Feb 2013 00:54:19 +1100 (EST) Received: from localhost ([::1]:33436 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U1H4L-0000Od-86 for incoming@patchwork.ozlabs.org; Fri, 01 Feb 2013 08:54:17 -0500 Received: from eggs.gnu.org ([208.118.235.92]:49542) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U1H46-0000HO-FG for qemu-devel@nongnu.org; Fri, 01 Feb 2013 08:54:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1U1H43-0006Sp-2T for qemu-devel@nongnu.org; Fri, 01 Feb 2013 08:54:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50281) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U1H42-0006Si-R3 for qemu-devel@nongnu.org; Fri, 01 Feb 2013 08:53:59 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r11DrupO016100 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 1 Feb 2013 08:53:57 -0500 Received: from localhost (ovpn-112-26.ams2.redhat.com [10.36.112.26]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r11DrtVU022380; Fri, 1 Feb 2013 08:53:56 -0500 From: Stefan Hajnoczi To: Date: Fri, 1 Feb 2013 14:53:21 +0100 Message-Id: <1359726808-11728-3-git-send-email-stefanha@redhat.com> In-Reply-To: <1359726808-11728-1-git-send-email-stefanha@redhat.com> References: <1359726808-11728-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Anthony Liguori , Jan Kiszka , Fabien Chouteau , Stefan Hajnoczi , Paolo Bonzini , Amos Kong Subject: [Qemu-devel] [PATCH v2 2/9] main-loop: switch to g_poll() on POSIX hosts X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Use g_poll(3) instead of select(2). Well, this is kind of a cheat. It's true that we're now using g_poll(3) on POSIX hosts but the *_fill() and *_poll() functions are still using rfds/wfds/xfds. We've set the scene to start converting *_fill() and *_poll() functions step-by-step until no more rfds/wfds/xfds users remain. Then we'll drop the temporary gpollfds_from_select() and gpollfds_to_select() functions and be left with native g_poll(2). On Windows things are a little crazy: convert from rfds/wfds/xfds to GPollFDs, back to rfds/wfds/xfds, call select(2), rfds/wfds/xfds back to GPollFDs, and finally back to rfds/wfds/xfds again. This is only temporary and keeps the Windows build working through the following patches. We'll drop this excessive conversion later and be left with a single GPollFDs -> select(2) -> GPollFDs sequence that allows Windows to use select(2) while the rest of QEMU only knows about GPollFD. Signed-off-by: Stefan Hajnoczi --- main-loop.c | 135 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 127 insertions(+), 8 deletions(-) diff --git a/main-loop.c b/main-loop.c index d0d8fe4..f1dcd14 100644 --- a/main-loop.c +++ b/main-loop.c @@ -117,6 +117,8 @@ void qemu_notify_event(void) aio_notify(qemu_aio_context); } +static GArray *gpollfds; + int qemu_init_main_loop(void) { int ret; @@ -133,6 +135,7 @@ int qemu_init_main_loop(void) return ret; } + gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD)); qemu_aio_context = aio_context_new(); src = aio_get_g_source(qemu_aio_context); g_source_attach(src, NULL); @@ -146,6 +149,62 @@ static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */ static int n_poll_fds; static int max_priority; +/* Load rfds/wfds/xfds into gpollfds. Will be removed a few commits later. */ +static void gpollfds_from_select(void) +{ + int fd; + for (fd = 0; fd <= nfds; fd++) { + int events = 0; + if (FD_ISSET(fd, &rfds)) { + events |= G_IO_IN | G_IO_HUP | G_IO_ERR; + } + if (FD_ISSET(fd, &wfds)) { + events |= G_IO_OUT | G_IO_ERR; + } + if (FD_ISSET(fd, &xfds)) { + events |= G_IO_PRI; + } + if (events) { + GPollFD pfd = { + .fd = fd, + .events = events, + }; + g_array_append_val(gpollfds, pfd); + } + } +} + +/* Store gpollfds revents into rfds/wfds/xfds. Will be removed a few commits + * later. + */ +static void gpollfds_to_select(int ret) +{ + int i; + + FD_ZERO(&rfds); + FD_ZERO(&wfds); + FD_ZERO(&xfds); + + if (ret <= 0) { + return; + } + + for (i = 0; i < gpollfds->len; i++) { + int fd = g_array_index(gpollfds, GPollFD, i).fd; + int revents = g_array_index(gpollfds, GPollFD, i).revents; + + if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) { + FD_SET(fd, &rfds); + } + if (revents & (G_IO_OUT | G_IO_ERR)) { + FD_SET(fd, &wfds); + } + if (revents & G_IO_PRI) { + FD_SET(fd, &xfds); + } + } +} + #ifndef _WIN32 static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds, fd_set *xfds, uint32_t *cur_timeout) @@ -212,22 +271,22 @@ static void glib_select_poll(fd_set *rfds, fd_set *wfds, fd_set *xfds, static int os_host_main_loop_wait(uint32_t timeout) { - struct timeval tv, *tvarg = NULL; int ret; glib_select_fill(&nfds, &rfds, &wfds, &xfds, &timeout); - if (timeout < UINT32_MAX) { - tvarg = &tv; - tv.tv_sec = timeout / 1000; - tv.tv_usec = (timeout % 1000) * 1000; - } - if (timeout > 0) { qemu_mutex_unlock_iothread(); } - ret = select(nfds + 1, &rfds, &wfds, &xfds, tvarg); + /* We'll eventually drop fd_set completely. But for now we still have + * *_fill() and *_poll() functions that use rfds/wfds/xfds. + */ + gpollfds_from_select(); + + ret = g_poll((GPollFD *)gpollfds->data, gpollfds->len, timeout); + + gpollfds_to_select(ret); if (timeout > 0) { qemu_mutex_lock_iothread(); @@ -327,6 +386,55 @@ void qemu_fd_register(int fd) FD_CONNECT | FD_WRITE | FD_OOB); } +static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds, + fd_set *xfds) +{ + int nfds = -1; + int i; + + for (i = 0; i < pollfds->len; i++) { + GPollFD *pfd = &g_array_index(pollfds, GPollFD, i); + int fd = pfd->fd; + int events = pfd->events; + if (events & (G_IO_IN | G_IO_HUP | G_IO_ERR)) { + FD_SET(fd, rfds); + nfds = MAX(nfds, fd); + } + if (events & (G_IO_OUT | G_IO_ERR)) { + FD_SET(fd, wfds); + nfds = MAX(nfds, fd); + } + if (events & G_IO_PRI) { + FD_SET(fd, xfds); + nfds = MAX(nfds, fd); + } + } + return nfds; +} + +static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds, + fd_set *wfds, fd_set *xfds) +{ + int i; + + for (i = 0; i < pollfds->len; i++) { + GPollFD *pfd = &g_array_index(pollfds, GPollFD, i); + int fd = pfd->fd; + int revents = 0; + + if (FD_ISSET(fd, rfds)) { + revents |= G_IO_IN | G_IO_HUP | G_IO_ERR; + } + if (FD_ISSET(fd, wfds)) { + revents |= G_IO_OUT | G_IO_ERR; + } + if (FD_ISSET(fd, xfds)) { + revents |= G_IO_PRI; + } + pfd->revents |= revents & pfd->events; + } +} + static int os_host_main_loop_wait(uint32_t timeout) { GMainContext *context = g_main_context_default(); @@ -382,12 +490,22 @@ static int os_host_main_loop_wait(uint32_t timeout) * improve socket latency. */ + /* This back-and-forth between GPollFDs and select(2) is temporary. We'll + * drop it in a couple of patches, I promise :). + */ + gpollfds_from_select(); + FD_ZERO(&rfds); + FD_ZERO(&wfds); + FD_ZERO(&xfds); + nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds); if (nfds >= 0) { select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0); if (select_ret != 0) { timeout = 0; + pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds); } } + gpollfds_to_select(select_ret || g_poll_ret); return select_ret || g_poll_ret; } @@ -403,6 +521,7 @@ int main_loop_wait(int nonblocking) } /* poll any events */ + g_array_set_size(gpollfds, 0); /* reset for new iteration */ /* XXX: separate device handlers from system ones */ nfds = -1; FD_ZERO(&rfds);