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[Qemu-devel] [RFC 3/3] linux-aio: poll ring for completions
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [RFC 3/3] linux-aio: poll ring for completions |
Date: |
Wed, 9 Nov 2016 17:13:22 +0000 |
The Linux AIO userspace ABI includes a ring that is shared with the
kernel. This allows userspace programs to process completions without
system calls.
Add an AioContext poll handler to check for completions in the ring.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/linux-aio.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/block/linux-aio.c b/block/linux-aio.c
index 1685ec2..58446dc 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -255,6 +255,21 @@ static void qemu_laio_completion_cb(EventNotifier *e)
}
}
+static bool laio_poll(void *opaque)
+{
+ LinuxAioState *s = opaque;
+ struct io_event *events;
+
+ return io_getevents_peek(s->ctx, &events);
+}
+
+static void laio_poll_handler(void *opaque)
+{
+ LinuxAioState *s = opaque;
+
+ qemu_laio_process_completions_and_submit(s);
+}
+
static void laio_cancel(BlockAIOCB *blockacb)
{
struct qemu_laiocb *laiocb = (struct qemu_laiocb *)blockacb;
@@ -440,6 +455,7 @@ BlockAIOCB *laio_submit(BlockDriverState *bs, LinuxAioState
*s, int fd,
void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context)
{
aio_set_event_notifier(old_context, &s->e, false, NULL);
+ aio_set_poll_handler(old_context, laio_poll, NULL, s);
qemu_bh_delete(s->completion_bh);
}
@@ -447,6 +463,7 @@ void laio_attach_aio_context(LinuxAioState *s, AioContext
*new_context)
{
s->aio_context = new_context;
s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
+ aio_set_poll_handler(new_context, laio_poll, laio_poll_handler, s);
aio_set_event_notifier(new_context, &s->e, false,
qemu_laio_completion_cb);
}
--
2.7.4