Commit 0836c72f authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Stefan Hajnoczi
Browse files

aio: push aio_context_acquire/release down to dispatching 



The AioContext data structures are now protected by list_lock and/or
they are walked with FOREACH_RCU primitives.  There is no need anymore
to acquire the AioContext for the entire duration of aio_dispatch.
Instead, just acquire it before and after invoking the callbacks.
The next step is then to push it further down.

Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-12-pbonzini@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent b20123a2

util/aio-posix.c

+11 −14
Original line number Diff line number Diff line
@@ -402,7 +402,9 @@ static bool aio_dispatch_handlers(AioContext *ctx) 
            (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&

            aio_node_check(ctx, node->is_external) &&

            node->io_read) {

            aio_context_acquire(ctx);

            node->io_read(node->opaque);

            aio_context_release(ctx);



            /* aio_notify() does not count as progress */

            if (node->opaque != &ctx->notifier) {
@@ -413,7 +415,9 @@ static bool aio_dispatch_handlers(AioContext *ctx) 
            (revents & (G_IO_OUT | G_IO_ERR)) &&

            aio_node_check(ctx, node->is_external) &&

            node->io_write) {

            aio_context_acquire(ctx);

            node->io_write(node->opaque);

            aio_context_release(ctx);

            progress = true;

        }
@@ -450,7 +454,9 @@ bool aio_dispatch(AioContext *ctx, bool dispatch_fds) 
    }



    /* Run our timers */

    aio_context_acquire(ctx);

    progress |= timerlistgroup_run_timers(&ctx->tlg);

    aio_context_release(ctx);



    return progress;

}
@@ -597,9 +603,6 @@ bool aio_poll(AioContext *ctx, bool blocking) 
    int64_t timeout;

    int64_t start = 0;



    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
@@ -617,9 +620,11 @@ bool aio_poll(AioContext *ctx, bool blocking) 
        start = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);

    }



    if (try_poll_mode(ctx, blocking)) {

        progress = true;

    } else {

    aio_context_acquire(ctx);

    progress = try_poll_mode(ctx, blocking);

    aio_context_release(ctx);



    if (!progress) {

        assert(npfd == 0);



        /* fill pollfds */
@@ -636,9 +641,6 @@ bool aio_poll(AioContext *ctx, bool blocking) 
        timeout = blocking ? aio_compute_timeout(ctx) : 0;



        /* wait until next event */

        if (timeout) {

            aio_context_release(ctx);

        }

        if (aio_epoll_check_poll(ctx, pollfds, npfd, timeout)) {

            AioHandler epoll_handler;
@@ -650,9 +652,6 @@ bool aio_poll(AioContext *ctx, bool blocking) 
        } else  {

            ret = qemu_poll_ns(pollfds, npfd, timeout);

        }

        if (timeout) {

            aio_context_acquire(ctx);

        }

    }



    if (blocking) {
@@ -717,8 +716,6 @@ bool aio_poll(AioContext *ctx, bool blocking) 
        progress = true;

    }



    aio_context_release(ctx);



    return progress;

}

util/aio-win32.c

+7 −8
Original line number Diff line number Diff line
@@ -266,7 +266,9 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) 
            (revents || event_notifier_get_handle(node->e) == event) &&

            node->io_notify) {

            node->pfd.revents = 0;

            aio_context_acquire(ctx);

            node->io_notify(node->e);

            aio_context_release(ctx);



            /* aio_notify() does not count as progress */

            if (node->e != &ctx->notifier) {
@@ -278,11 +280,15 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) 
            (node->io_read || node->io_write)) {

            node->pfd.revents = 0;

            if ((revents & G_IO_IN) && node->io_read) {

                aio_context_acquire(ctx);

                node->io_read(node->opaque);

                aio_context_release(ctx);

                progress = true;

            }

            if ((revents & G_IO_OUT) && node->io_write) {

                aio_context_acquire(ctx);

                node->io_write(node->opaque);

                aio_context_release(ctx);

                progress = true;

            }
@@ -329,7 +335,6 @@ bool aio_poll(AioContext *ctx, bool blocking) 
    int count;

    int timeout;



    aio_context_acquire(ctx);

    progress = false;



    /* aio_notify can avoid the expensive event_notifier_set if
@@ -371,17 +376,11 @@ bool aio_poll(AioContext *ctx, bool blocking) 


        timeout = blocking && !have_select_revents

            ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;

        if (timeout) {

            aio_context_release(ctx);

        }

        ret = WaitForMultipleObjects(count, events, FALSE, timeout);

        if (blocking) {

            assert(first);

            atomic_sub(&ctx->notify_me, 2);

        }

        if (timeout) {

            aio_context_acquire(ctx);

        }



        if (first) {

            aio_notify_accept(ctx);
@@ -404,8 +403,8 @@ bool aio_poll(AioContext *ctx, bool blocking) 
        progress |= aio_dispatch_handlers(ctx, event);

    } while (count > 0);



    aio_context_acquire(ctx);

    progress |= timerlistgroup_run_timers(&ctx->tlg);



    aio_context_release(ctx);

    return progress;

}

util/async.c

+2 −0
Original line number Diff line number Diff line
@@ -114,7 +114,9 @@ int aio_bh_poll(AioContext *ctx) 
                ret = 1;

            }

            bh->idle = 0;

            aio_context_acquire(ctx);

            aio_bh_call(bh);

            aio_context_release(ctx);

        }

        if (bh->deleted) {

            deleted = true;