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authorStefan Hajnoczi <stefanha@redhat.com>2013-02-20 11:28:25 +0100
committerAnthony Liguori <aliguori@us.ibm.com>2013-02-21 16:17:30 -0600
commitcbff4b342b000a7642125dbdabf61113e05eee44 (patch)
tree6243a0867a869baaca82e328da42e5fe98b74da6
parent134a03e0b3d34b01b68107104c525c3bff1211d4 (diff)
downloadqemu-arm-cbff4b342b000a7642125dbdabf61113e05eee44.tar.gz
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 <stefanha@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Message-id: 1361356113-11049-3-git-send-email-stefanha@redhat.com Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
-rw-r--r--main-loop.c137
1 files changed, 129 insertions, 8 deletions
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);