X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=aio-posix.c;h=43162a9f29164697c28e2f7990f596deacefb61f;hb=c4bf37e0b0f09d9f51d8407c3e51093d44348008;hp=fe4dbb4523e6fcc8272ff5f19c2ef07c9160fd25;hpb=177f7fc6884c47666f6c6eeca376a92432ccda38;p=mirror_qemu.git

diff --git a/aio-posix.c b/aio-posix.c
index fe4dbb4523..43162a9f29 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -13,22 +13,182 @@
  * GNU GPL, version 2 or (at your option) any later version.
  */
 
+#include "qemu/osdep.h"
 #include "qemu-common.h"
 #include "block/block.h"
 #include "qemu/queue.h"
 #include "qemu/sockets.h"
+#ifdef CONFIG_EPOLL_CREATE1
+#include <sys/epoll.h>
+#endif
 
 struct AioHandler
 {
     GPollFD pfd;
     IOHandler *io_read;
     IOHandler *io_write;
-    AioFlushHandler *io_flush;
     int deleted;
     void *opaque;
+    bool is_external;
     QLIST_ENTRY(AioHandler) node;
 };
 
+#ifdef CONFIG_EPOLL_CREATE1
+
+/* The fd number threashold to switch to epoll */
+#define EPOLL_ENABLE_THRESHOLD 64
+
+static void aio_epoll_disable(AioContext *ctx)
+{
+    ctx->epoll_available = false;
+    if (!ctx->epoll_enabled) {
+        return;
+    }
+    ctx->epoll_enabled = false;
+    close(ctx->epollfd);
+}
+
+static inline int epoll_events_from_pfd(int pfd_events)
+{
+    return (pfd_events & G_IO_IN ? EPOLLIN : 0) |
+           (pfd_events & G_IO_OUT ? EPOLLOUT : 0) |
+           (pfd_events & G_IO_HUP ? EPOLLHUP : 0) |
+           (pfd_events & G_IO_ERR ? EPOLLERR : 0);
+}
+
+static bool aio_epoll_try_enable(AioContext *ctx)
+{
+    AioHandler *node;
+    struct epoll_event event;
+
+    QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+        int r;
+        if (node->deleted || !node->pfd.events) {
+            continue;
+        }
+        event.events = epoll_events_from_pfd(node->pfd.events);
+        event.data.ptr = node;
+        r = epoll_ctl(ctx->epollfd, EPOLL_CTL_ADD, node->pfd.fd, &event);
+        if (r) {
+            return false;
+        }
+    }
+    ctx->epoll_enabled = true;
+    return true;
+}
+
+static void aio_epoll_update(AioContext *ctx, AioHandler *node, bool is_new)
+{
+    struct epoll_event event;
+    int r;
+
+    if (!ctx->epoll_enabled) {
+        return;
+    }
+    if (!node->pfd.events) {
+        r = epoll_ctl(ctx->epollfd, EPOLL_CTL_DEL, node->pfd.fd, &event);
+        if (r) {
+            aio_epoll_disable(ctx);
+        }
+    } else {
+        event.data.ptr = node;
+        event.events = epoll_events_from_pfd(node->pfd.events);
+        if (is_new) {
+            r = epoll_ctl(ctx->epollfd, EPOLL_CTL_ADD, node->pfd.fd, &event);
+            if (r) {
+                aio_epoll_disable(ctx);
+            }
+        } else {
+            r = epoll_ctl(ctx->epollfd, EPOLL_CTL_MOD, node->pfd.fd, &event);
+            if (r) {
+                aio_epoll_disable(ctx);
+            }
+        }
+    }
+}
+
+static int aio_epoll(AioContext *ctx, GPollFD *pfds,
+                     unsigned npfd, int64_t timeout)
+{
+    AioHandler *node;
+    int i, ret = 0;
+    struct epoll_event events[128];
+
+    assert(npfd == 1);
+    assert(pfds[0].fd == ctx->epollfd);
+    if (timeout > 0) {
+        ret = qemu_poll_ns(pfds, npfd, timeout);
+    }
+    if (timeout <= 0 || ret > 0) {
+        ret = epoll_wait(ctx->epollfd, events,
+                         sizeof(events) / sizeof(events[0]),
+                         timeout);
+        if (ret <= 0) {
+            goto out;
+        }
+        for (i = 0; i < ret; i++) {
+            int ev = events[i].events;
+            node = events[i].data.ptr;
+            node->pfd.revents = (ev & EPOLLIN ? G_IO_IN : 0) |
+                (ev & EPOLLOUT ? G_IO_OUT : 0) |
+                (ev & EPOLLHUP ? G_IO_HUP : 0) |
+                (ev & EPOLLERR ? G_IO_ERR : 0);
+        }
+    }
+out:
+    return ret;
+}
+
+static bool aio_epoll_enabled(AioContext *ctx)
+{
+    /* Fall back to ppoll when external clients are disabled. */
+    return !aio_external_disabled(ctx) && ctx->epoll_enabled;
+}
+
+static bool aio_epoll_check_poll(AioContext *ctx, GPollFD *pfds,
+                                 unsigned npfd, int64_t timeout)
+{
+    if (!ctx->epoll_available) {
+        return false;
+    }
+    if (aio_epoll_enabled(ctx)) {
+        return true;
+    }
+    if (npfd >= EPOLL_ENABLE_THRESHOLD) {
+        if (aio_epoll_try_enable(ctx)) {
+            return true;
+        } else {
+            aio_epoll_disable(ctx);
+        }
+    }
+    return false;
+}
+
+#else
+
+static void aio_epoll_update(AioContext *ctx, AioHandler *node, bool is_new)
+{
+}
+
+static int aio_epoll(AioContext *ctx, GPollFD *pfds,
+                     unsigned npfd, int64_t timeout)
+{
+    assert(false);
+}
+
+static bool aio_epoll_enabled(AioContext *ctx)
+{
+    return false;
+}
+
+static bool aio_epoll_check_poll(AioContext *ctx, GPollFD *pfds,
+                          unsigned npfd, int64_t timeout)
+{
+    return false;
+}
+
+#endif
+
 static AioHandler *find_aio_handler(AioContext *ctx, int fd)
 {
     AioHandler *node;
@@ -44,12 +204,14 @@ static AioHandler *find_aio_handler(AioContext *ctx, int fd)
 
 void aio_set_fd_handler(AioContext *ctx,
                         int fd,
+                        bool is_external,
                         IOHandler *io_read,
                         IOHandler *io_write,
-                        AioFlushHandler *io_flush,
                         void *opaque)
 {
     AioHandler *node;
+    bool is_new = false;
+    bool deleted = false;
 
     node = find_aio_handler(ctx, fd);
 
@@ -68,39 +230,48 @@ void aio_set_fd_handler(AioContext *ctx,
                  * releasing the walking_handlers lock.
                  */
                 QLIST_REMOVE(node, node);
-                g_free(node);
+                deleted = true;
             }
         }
     } else {
         if (node == NULL) {
             /* Alloc and insert if it's not already there */
-            node = g_malloc0(sizeof(AioHandler));
+            node = g_new0(AioHandler, 1);
             node->pfd.fd = fd;
             QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
 
             g_source_add_poll(&ctx->source, &node->pfd);
+            is_new = true;
         }
         /* Update handler with latest information */
         node->io_read = io_read;
         node->io_write = io_write;
-        node->io_flush = io_flush;
         node->opaque = opaque;
+        node->is_external = is_external;
 
-        node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP : 0);
-        node->pfd.events |= (io_write ? G_IO_OUT : 0);
+        node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0);
+        node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0);
     }
 
+    aio_epoll_update(ctx, node, is_new);
     aio_notify(ctx);
+    if (deleted) {
+        g_free(node);
+    }
 }
 
 void aio_set_event_notifier(AioContext *ctx,
                             EventNotifier *notifier,
-                            EventNotifierHandler *io_read,
-                            AioFlushEventNotifierHandler *io_flush)
+                            bool is_external,
+                            EventNotifierHandler *io_read)
 {
     aio_set_fd_handler(ctx, event_notifier_get_fd(notifier),
-                       (IOHandler *)io_read, NULL,
-                       (AioFlushHandler *)io_flush, notifier);
+                       is_external, (IOHandler *)io_read, NULL, notifier);
+}
+
+bool aio_prepare(AioContext *ctx)
+{
+    return false;
 }
 
 bool aio_pending(AioContext *ctx)
@@ -110,18 +281,13 @@ bool aio_pending(AioContext *ctx)
     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
         int revents;
 
-        /*
-         * FIXME: right now we cannot get G_IO_HUP and G_IO_ERR because
-         * main-loop.c is still select based (due to the slirp legacy).
-         * If main-loop.c ever switches to poll, G_IO_ERR should be
-         * tested too.  Dispatching G_IO_ERR to both handlers should be
-         * okay, since handlers need to be ready for spurious wakeups.
-         */
         revents = node->pfd.revents & node->pfd.events;
-        if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
+        if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read &&
+            aio_node_check(ctx, node->is_external)) {
             return true;
         }
-        if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
+        if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write &&
+            aio_node_check(ctx, node->is_external)) {
             return true;
         }
     }
@@ -129,31 +295,22 @@ bool aio_pending(AioContext *ctx)
     return false;
 }
 
-bool aio_poll(AioContext *ctx, bool blocking)
+bool aio_dispatch(AioContext *ctx)
 {
-    static struct timeval tv0;
     AioHandler *node;
-    fd_set rdfds, wrfds;
-    int max_fd = -1;
-    int ret;
-    bool busy, progress;
-
-    progress = false;
+    bool progress = false;
 
     /*
-     * If there are callbacks left that have been queued, we need to call then.
+     * If there are callbacks left that have been queued, we need to call them.
      * Do not call select in this case, because it is possible that the caller
-     * does not need a complete flush (as is the case for qemu_aio_wait loops).
+     * does not need a complete flush (as is the case for aio_poll loops).
      */
     if (aio_bh_poll(ctx)) {
-        blocking = false;
         progress = true;
     }
 
     /*
-     * Then dispatch any pending callbacks from the GSource.
-     *
-     * We have to walk very carefully in case qemu_aio_set_fd_handler is
+     * We have to walk very carefully in case aio_set_fd_handler is
      * called while we're walking.
      */
     node = QLIST_FIRST(&ctx->aio_handlers);
@@ -166,12 +323,21 @@ bool aio_poll(AioContext *ctx, bool blocking)
         revents = node->pfd.revents & node->pfd.events;
         node->pfd.revents = 0;
 
-        /* See comment in aio_pending.  */
-        if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
+        if (!node->deleted &&
+            (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
+            aio_node_check(ctx, node->is_external) &&
+            node->io_read) {
             node->io_read(node->opaque);
-            progress = true;
+
+            /* aio_notify() does not count as progress */
+            if (node->opaque != &ctx->notifier) {
+                progress = true;
+            }
         }
-        if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
+        if (!node->deleted &&
+            (revents & (G_IO_OUT | G_IO_ERR)) &&
+            aio_node_check(ctx, node->is_external) &&
+            node->io_write) {
             node->io_write(node->opaque);
             progress = true;
         }
@@ -187,83 +353,148 @@ bool aio_poll(AioContext *ctx, bool blocking)
         }
     }
 
-    if (progress && !blocking) {
-        return true;
+    /* Run our timers */
+    progress |= timerlistgroup_run_timers(&ctx->tlg);
+
+    return progress;
+}
+
+/* These thread-local variables are used only in a small part of aio_poll
+ * around the call to the poll() system call.  In particular they are not
+ * used while aio_poll is performing callbacks, which makes it much easier
+ * to think about reentrancy!
+ *
+ * Stack-allocated arrays would be perfect but they have size limitations;
+ * heap allocation is expensive enough that we want to reuse arrays across
+ * calls to aio_poll().  And because poll() has to be called without holding
+ * any lock, the arrays cannot be stored in AioContext.  Thread-local data
+ * has none of the disadvantages of these three options.
+ */
+static __thread GPollFD *pollfds;
+static __thread AioHandler **nodes;
+static __thread unsigned npfd, nalloc;
+static __thread Notifier pollfds_cleanup_notifier;
+
+static void pollfds_cleanup(Notifier *n, void *unused)
+{
+    g_assert(npfd == 0);
+    g_free(pollfds);
+    g_free(nodes);
+    nalloc = 0;
+}
+
+static void add_pollfd(AioHandler *node)
+{
+    if (npfd == nalloc) {
+        if (nalloc == 0) {
+            pollfds_cleanup_notifier.notify = pollfds_cleanup;
+            qemu_thread_atexit_add(&pollfds_cleanup_notifier);
+            nalloc = 8;
+        } else {
+            g_assert(nalloc <= INT_MAX);
+            nalloc *= 2;
+        }
+        pollfds = g_renew(GPollFD, pollfds, nalloc);
+        nodes = g_renew(AioHandler *, nodes, nalloc);
+    }
+    nodes[npfd] = node;
+    pollfds[npfd] = (GPollFD) {
+        .fd = node->pfd.fd,
+        .events = node->pfd.events,
+    };
+    npfd++;
+}
+
+bool aio_poll(AioContext *ctx, bool blocking)
+{
+    AioHandler *node;
+    int i, ret;
+    bool progress;
+    int64_t timeout;
+
+    aio_context_acquire(ctx);
+    progress = false;
+
+    /* aio_notify can avoid the expensive event_notifier_set if
+     * everything (file descriptors, bottom halves, timers) will
+     * be re-evaluated before the next blocking poll().  This is
+     * already true when aio_poll is called with blocking == false;
+     * if blocking == true, it is only true after poll() returns,
+     * so disable the optimization now.
+     */
+    if (blocking) {
+        atomic_add(&ctx->notify_me, 2);
     }
 
     ctx->walking_handlers++;
 
-    FD_ZERO(&rdfds);
-    FD_ZERO(&wrfds);
+    assert(npfd == 0);
 
-    /* fill fd sets */
-    busy = false;
+    /* fill pollfds */
     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
-        /* If there aren't pending AIO operations, don't invoke callbacks.
-         * Otherwise, if there are no AIO requests, qemu_aio_wait() would
-         * wait indefinitely.
-         */
-        if (!node->deleted && node->io_flush) {
-            if (node->io_flush(node->opaque) == 0) {
-                continue;
-            }
-            busy = true;
-        }
-        if (!node->deleted && node->io_read) {
-            FD_SET(node->pfd.fd, &rdfds);
-            max_fd = MAX(max_fd, node->pfd.fd + 1);
-        }
-        if (!node->deleted && node->io_write) {
-            FD_SET(node->pfd.fd, &wrfds);
-            max_fd = MAX(max_fd, node->pfd.fd + 1);
+        if (!node->deleted && node->pfd.events
+            && !aio_epoll_enabled(ctx)
+            && aio_node_check(ctx, node->is_external)) {
+            add_pollfd(node);
         }
     }
 
-    ctx->walking_handlers--;
+    timeout = blocking ? aio_compute_timeout(ctx) : 0;
 
-    /* No AIO operations?  Get us out of here */
-    if (!busy) {
-        return progress;
+    /* wait until next event */
+    if (timeout) {
+        aio_context_release(ctx);
+    }
+    if (aio_epoll_check_poll(ctx, pollfds, npfd, timeout)) {
+        AioHandler epoll_handler;
+
+        epoll_handler.pfd.fd = ctx->epollfd;
+        epoll_handler.pfd.events = G_IO_IN | G_IO_OUT | G_IO_HUP | G_IO_ERR;
+        npfd = 0;
+        add_pollfd(&epoll_handler);
+        ret = aio_epoll(ctx, pollfds, npfd, timeout);
+    } else  {
+        ret = qemu_poll_ns(pollfds, npfd, timeout);
+    }
+    if (blocking) {
+        atomic_sub(&ctx->notify_me, 2);
+    }
+    if (timeout) {
+        aio_context_acquire(ctx);
     }
 
-    /* wait until next event */
-    ret = select(max_fd, &rdfds, &wrfds, NULL, blocking ? NULL : &tv0);
+    aio_notify_accept(ctx);
 
     /* if we have any readable fds, dispatch event */
     if (ret > 0) {
-        /* we have to walk very carefully in case
-         * qemu_aio_set_fd_handler is called while we're walking */
-        node = QLIST_FIRST(&ctx->aio_handlers);
-        while (node) {
-            AioHandler *tmp;
-
-            ctx->walking_handlers++;
-
-            if (!node->deleted &&
-                FD_ISSET(node->pfd.fd, &rdfds) &&
-                node->io_read) {
-                node->io_read(node->opaque);
-                progress = true;
-            }
-            if (!node->deleted &&
-                FD_ISSET(node->pfd.fd, &wrfds) &&
-                node->io_write) {
-                node->io_write(node->opaque);
-                progress = true;
-            }
-
-            tmp = node;
-            node = QLIST_NEXT(node, node);
+        for (i = 0; i < npfd; i++) {
+            nodes[i]->pfd.revents = pollfds[i].revents;
+        }
+    }
 
-            ctx->walking_handlers--;
+    npfd = 0;
+    ctx->walking_handlers--;
 
-            if (!ctx->walking_handlers && tmp->deleted) {
-                QLIST_REMOVE(tmp, node);
-                g_free(tmp);
-            }
-        }
+    /* Run dispatch even if there were no readable fds to run timers */
+    if (aio_dispatch(ctx)) {
+        progress = true;
     }
 
-    assert(progress || busy);
-    return true;
+    aio_context_release(ctx);
+
+    return progress;
+}
+
+void aio_context_setup(AioContext *ctx)
+{
+#ifdef CONFIG_EPOLL_CREATE1
+    assert(!ctx->epollfd);
+    ctx->epollfd = epoll_create1(EPOLL_CLOEXEC);
+    if (ctx->epollfd == -1) {
+        fprintf(stderr, "Failed to create epoll instance: %s", strerror(errno));
+        ctx->epoll_available = false;
+    } else {
+        ctx->epoll_available = true;
+    }
+#endif
 }