From cbff4b342b000a7642125dbdabf61113e05eee44 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 20 Feb 2013 11:28:25 +0100 Subject: main-loop: switch to g_poll() on POSIX hosts 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 Reviewed-by: Laszlo Ersek Message-id: 1361356113-11049-3-git-send-email-stefanha@redhat.com Signed-off-by: Anthony Liguori --- main-loop.c | 137 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 129 insertions(+), 8 deletions(-) (limited to 'main-loop.c') diff --git a/main-loop.c b/main-loop.c index d0d8fe4950..489b27c1f6 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 +490,24 @@ 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; } + if (select_ret > 0) { + pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds); + } } + gpollfds_to_select(select_ret); return select_ret || g_poll_ret; } @@ -403,6 +523,7 @@ 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); -- cgit v1.2.3