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authorFabiano Rosas <farosas@suse.de>2024-02-29 12:29:55 -0300
committerPeter Xu <peterx@redhat.com>2024-03-01 15:42:04 +0800
commit4aac6b1e9bd48677c4f24518fe86ffd34c677d5a (patch)
tree4be5f25915163f70d265b4f05bbd7a7230515cee
parent2b571432314ab42da742fbb578f4174166ecd7f5 (diff)
downloadfocaccia-qemu-4aac6b1e9bd48677c4f24518fe86ffd34c677d5a.tar.gz
focaccia-qemu-4aac6b1e9bd48677c4f24518fe86ffd34c677d5a.zip
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>
-rw-r--r--migration/multifd.c17
-rw-r--r--migration/trace-events2
2 files changed, 14 insertions, 5 deletions
diff --git a/migration/multifd.c b/migration/multifd.c
index 6c07f19af1..c7389bf833 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -1182,18 +1182,27 @@ void multifd_recv_cleanup(void)
 
 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 298ad2b0dd..bf1a069632 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -132,7 +132,7 @@ multifd_recv(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags, uin
 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"