[v2,2/6] migration/multifd: notify channels_ready when send thread starts
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Message ID 20191026004520.5515-3-richardw.yang@linux.intel.com
State New
Headers show
Series
  • migration/multifd: a new mechanism for send thread sync
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Commit Message

Wei Yang Oct. 26, 2019, 12:45 a.m. UTC
multifd_send_state->channels_ready is initialized to 0. It is proper to
let main thread know we are ready when thread start running.

Current implementation works since ram_save_setup() calls
multifd_send_sync_main() which wake up send thread and posts
channels_ready. This behavior will introduce some unpredictable
situation and disturb the semaphore value.

This is a preparation patch to use another mechanism to do send thread
synchronization to avoid post channels_ready in this case. So this patch
posts channels_ready when send threads start running.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
---
 migration/ram.c | 2 ++
 1 file changed, 2 insertions(+)

Patch
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diff --git a/migration/ram.c b/migration/ram.c
index 35f147388b..25d477796e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1107,6 +1107,8 @@  static void *multifd_send_thread(void *opaque)
     }
     /* initial packet */
     p->num_packets = 1;
+    /* let main thread know we are ready */
+    qemu_sem_post(&multifd_send_state->channels_ready);
 
     while (true) {
         qemu_sem_wait(&p->sem);