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[Qemu-devel] [PATCH v2 5/5] iothread: document about why we need explici
From: |
Peter Xu |
Subject: |
[Qemu-devel] [PATCH v2 5/5] iothread: document about why we need explicit aio_poll() |
Date: |
Wed, 6 Mar 2019 19:55:32 +0800 |
After consulting Paolo I know why we'd better keep the explicit
aio_poll() in iothread_run(). Document it directly into the code so
that future readers will know the answer from day one.
Signed-off-by: Peter Xu <address@hidden>
---
iothread.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/iothread.c b/iothread.c
index 045825a348..14e9f3779e 100644
--- a/iothread.c
+++ b/iothread.c
@@ -64,6 +64,15 @@ static void *iothread_run(void *opaque)
qemu_sem_post(&iothread->init_done_sem);
while (iothread->running) {
+ /*
+ * Note: from functional-wise the g_main_loop_run() below can
+ * already cover the aio_poll() events, but we can't run the
+ * main loop unconditionally because explicit aio_poll() here
+ * is faster than g_main_loop_run() when we do not need the
+ * gcontext at all (e.g., pure block layer iothreads). In
+ * other words, when we want to run the gcontext with the
+ * iothread we need to pay some performance for functionality.
+ */
aio_poll(iothread->ctx, true);
/*
--
2.17.1
- [Qemu-devel] [PATCH v2 0/5] iothread: create gcontext unconditionally, Peter Xu, 2019/03/06
- [Qemu-devel] [PATCH v2 1/5] iothread: replace init_done_cond with a semaphore, Peter Xu, 2019/03/06
- [Qemu-devel] [PATCH v2 2/5] iothread: create the gcontext unconditionally, Peter Xu, 2019/03/06
- [Qemu-devel] [PATCH v2 3/5] iothread: create main loop unconditionally, Peter Xu, 2019/03/06
- [Qemu-devel] [PATCH v2 4/5] iothread: push gcontext earlier in the thread_fn, Peter Xu, 2019/03/06
- [Qemu-devel] [PATCH v2 5/5] iothread: document about why we need explicit aio_poll(),
Peter Xu <=
- Re: [Qemu-devel] [PATCH v2 0/5] iothread: create gcontext unconditionally, Stefan Hajnoczi, 2019/03/08