target-i386: Rewrite gen_enter inline

[qemu.git] / aio-posix.c

diff --git a/aio-posix.c b/aio-posix.c
index f921d4f538337c30e58abd7f1b3565c79c155ff4..fa7f8ab2a5a1c59f2aa72690c451ce6af53d6b51 100644 (file)
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -13,10 +13,14 @@
  * GNU GPL, version 2 or (at your option) any later version.
  */
 
  * 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"
 #include "qemu-common.h"
 #include "block/block.h"
 #include "qemu/queue.h"
 #include "qemu/sockets.h"

+#ifdef CONFIG_EPOLL
+#include <sys/epoll.h>
+#endif

 
 struct AioHandler
 {
 
 struct AioHandler
 {


@@ -24,11 +28,167 @@ struct AioHandler
     IOHandler *io_read;
     IOHandler *io_write;
     int deleted;
     IOHandler *io_read;
     IOHandler *io_write;
     int deleted;

-    int pollfds_idx;

     void *opaque;
     void *opaque;

+    bool is_external;

     QLIST_ENTRY(AioHandler) node;
 };
 
     QLIST_ENTRY(AioHandler) node;
 };
 

+#ifdef CONFIG_EPOLL
+
+/* 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;
 static AioHandler *find_aio_handler(AioContext *ctx, int fd)
 {
     AioHandler *node;


@@ -44,11 +204,14 @@ static AioHandler *find_aio_handler(AioContext *ctx, int fd)
 
 void aio_set_fd_handler(AioContext *ctx,
                         int fd,
 
 void aio_set_fd_handler(AioContext *ctx,
                         int fd,

+                        bool is_external,

                         IOHandler *io_read,
                         IOHandler *io_write,
                         void *opaque)
 {
     AioHandler *node;
                         IOHandler *io_read,
                         IOHandler *io_write,
                         void *opaque)
 {
     AioHandler *node;

+    bool is_new = false;
+    bool deleted = false;

 
     node = find_aio_handler(ctx, fd);
 
 
     node = find_aio_handler(ctx, fd);
 


@@ -67,37 +230,48 @@ void aio_set_fd_handler(AioContext *ctx,
                  * releasing the walking_handlers lock.
                  */
                 QLIST_REMOVE(node, node);
                  * 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 */
             }
         }
     } 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);
             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->opaque = opaque;
         }
         /* Update handler with latest information */
         node->io_read = io_read;
         node->io_write = io_write;
         node->opaque = opaque;

-        node->pollfds_idx = -1;
+        node->is_external = is_external;

 
         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);
     }
 
 
         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);
     aio_notify(ctx);

+    if (deleted) {
+        g_free(node);
+    }

 }
 
 void aio_set_event_notifier(AioContext *ctx,
                             EventNotifier *notifier,
 }
 
 void aio_set_event_notifier(AioContext *ctx,
                             EventNotifier *notifier,

+                            bool is_external,

                             EventNotifierHandler *io_read)
 {
     aio_set_fd_handler(ctx, event_notifier_get_fd(notifier),
                             EventNotifierHandler *io_read)
 {
     aio_set_fd_handler(ctx, event_notifier_get_fd(notifier),

-                       (IOHandler *)io_read, NULL, notifier);
+                       is_external, (IOHandler *)io_read, NULL, notifier);
+}
+
+bool aio_prepare(AioContext *ctx)
+{
+    return false;

 }
 
 bool aio_pending(AioContext *ctx)
 }
 
 bool aio_pending(AioContext *ctx)


@@ -119,13 +293,22 @@ bool aio_pending(AioContext *ctx)
     return false;
 }
 
     return false;
 }
 

-static bool aio_dispatch(AioContext *ctx)
+bool aio_dispatch(AioContext *ctx)

 {
     AioHandler *node;
     bool progress = false;
 
     /*
 {
     AioHandler *node;
     bool progress = false;
 
     /*

-     * We have to walk very carefully in case qemu_aio_set_fd_handler is
+     * 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 aio_poll loops).
+     */
+    if (aio_bh_poll(ctx)) {
+        progress = true;
+    }
+
+    /*
+     * We have to walk very carefully in case aio_set_fd_handler is

      * called while we're walking.
      */
     node = QLIST_FIRST(&ctx->aio_handlers);
      * called while we're walking.
      */
     node = QLIST_FIRST(&ctx->aio_handlers);


@@ -172,71 +355,141 @@ static bool aio_dispatch(AioContext *ctx)
     return progress;
 }
 
     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;
 bool aio_poll(AioContext *ctx, bool blocking)
 {
     AioHandler *node;

-    int ret;
+    int i, ret;

     bool progress;
     bool progress;

+    int64_t timeout;

 
 

+    aio_context_acquire(ctx);

     progress = false;
 
     progress = false;
 

-    /*
-     * 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).
+    /* 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 (aio_bh_poll(ctx)) {
-        blocking = false;
-        progress = true;
-    }
-
-    if (aio_dispatch(ctx)) {
-        progress = true;
-    }
-
-    if (progress && !blocking) {
-        return true;
+    if (blocking) {
+        atomic_add(&ctx->notify_me, 2);

     }
 
     ctx->walking_handlers++;
 
     }
 
     ctx->walking_handlers++;
 

-    g_array_set_size(ctx->pollfds, 0);
+    assert(npfd == 0);

 
     /* fill pollfds */
     QLIST_FOREACH(node, &ctx->aio_handlers, node) {
 
     /* fill pollfds */
     QLIST_FOREACH(node, &ctx->aio_handlers, node) {

-        node->pollfds_idx = -1;
-        if (!node->deleted && node->pfd.events) {
-            GPollFD pfd = {
-                .fd = node->pfd.fd,
-                .events = node->pfd.events,
-            };
-            node->pollfds_idx = ctx->pollfds->len;
-            g_array_append_val(ctx->pollfds, pfd);
+        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;

 
     /* wait until next event */
 
     /* wait until next event */

-    ret = qemu_poll_ns((GPollFD *)ctx->pollfds->data,
-                         ctx->pollfds->len,
-                         blocking ? timerlistgroup_deadline_ns(&ctx->tlg) : 0);
+    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);
+    }
+
+    aio_notify_accept(ctx);

 
     /* if we have any readable fds, dispatch event */
     if (ret > 0) {
 
     /* if we have any readable fds, dispatch event */
     if (ret > 0) {

-        QLIST_FOREACH(node, &ctx->aio_handlers, node) {
-            if (node->pollfds_idx != -1) {
-                GPollFD *pfd = &g_array_index(ctx->pollfds, GPollFD,
-                                              node->pollfds_idx);
-                node->pfd.revents = pfd->revents;
-            }
+        for (i = 0; i < npfd; i++) {
+            nodes[i]->pfd.revents = pollfds[i].revents;

         }
     }
 
         }
     }
 

+    npfd = 0;
+    ctx->walking_handlers--;
+

     /* Run dispatch even if there were no readable fds to run timers */
     if (aio_dispatch(ctx)) {
         progress = true;
     }
 
     /* Run dispatch even if there were no readable fds to run timers */
     if (aio_dispatch(ctx)) {
         progress = true;
     }
 

+    aio_context_release(ctx);
+

     return progress;
 }
     return progress;
 }

+
+void aio_context_setup(AioContext *ctx, Error **errp)
+{
+#ifdef CONFIG_EPOLL
+    assert(!ctx->epollfd);
+    ctx->epollfd = epoll_create1(EPOLL_CLOEXEC);
+    if (ctx->epollfd == -1) {
+        ctx->epoll_available = false;
+    } else {
+        ctx->epoll_available = true;
+    }
+#endif
+}