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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: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-12-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-02-13 14:52:28 +01:00 committed by Stefan Hajnoczi
parent b20123a28b
commit 0836c72f70
3 changed files with 20 additions and 22 deletions
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25
util/aio-posix.c
View File

@ -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;
}

15
util/aio-win32.c
View File

@ -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;
}

2
util/async.c
View File

@ -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;