migration/multifd: Cleanup multifd_recv_sync_main
Some minor cleanups and documentation for multifd_recv_sync_main.
Use thread_count as done in other parts of the code. Remove p->id from
the multifd_recv_state sync, since that is global and not tied to a
channel. Add documentation for the sync steps.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-2-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
diff --git a/migration/multifd.c b/migration/multifd.c
index 6c07f19..c7389bf 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -1182,18 +1182,27 @@
void multifd_recv_sync_main(void)
{
+ int thread_count = migrate_multifd_channels();
int i;
if (!migrate_multifd()) {
return;
}
- for (i = 0; i < migrate_multifd_channels(); i++) {
- MultiFDRecvParams *p = &multifd_recv_state->params[i];
- trace_multifd_recv_sync_main_wait(p->id);
+ /*
+ * Initiate the synchronization by waiting for all channels.
+ * For socket-based migration this means each channel has received
+ * the SYNC packet on the stream.
+ */
+ for (i = 0; i < thread_count; i++) {
+ trace_multifd_recv_sync_main_wait(i);
qemu_sem_wait(&multifd_recv_state->sem_sync);
}
- for (i = 0; i < migrate_multifd_channels(); i++) {
+
+ /*
+ * Sync done. Release the channels for the next iteration.
+ */
+ for (i = 0; i < thread_count; i++) {
MultiFDRecvParams *p = &multifd_recv_state->params[i];
WITH_QEMU_LOCK_GUARD(&p->mutex) {
diff --git a/migration/trace-events b/migration/trace-events
index 298ad2b..bf1a069 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -132,7 +132,7 @@
multifd_recv_new_channel(uint8_t id) "channel %u"
multifd_recv_sync_main(long packet_num) "packet num %ld"
multifd_recv_sync_main_signal(uint8_t id) "channel %u"
-multifd_recv_sync_main_wait(uint8_t id) "channel %u"
+multifd_recv_sync_main_wait(uint8_t id) "iter %u"
multifd_recv_terminate_threads(bool error) "error %d"
multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %u packets %" PRIu64 " pages %" PRIu64
multifd_recv_thread_start(uint8_t id) "%u"
