Some errors, like the lack of Scatter-Gather support by the network
interface(NETIF_F_SG) may cause sendmsg(...,MSG_ZEROCOPY) to fail on using
zero-copy, which causes it to fall back to the default copying mechanism.
After each full dirty-bitmap scan there should be a zero-copy flush
happening, which checks for errors each of the previous calls to
sendmsg(...,MSG_ZEROCOPY). If all of them failed to use zero-copy, then
increment zero_copy_copied migration stat to let the user know about it.
Signed-off-by: Leonardo Bras <leob...@redhat.com>
---
migration/ram.h | 2 ++
migration/multifd.c | 2 ++
migration/ram.c | 5 +++++
3 files changed, 9 insertions(+)
diff --git a/migration/ram.h b/migration/ram.h
index ded0a3a086..f6753f1354 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -87,4 +87,6 @@ void ram_write_tracking_prepare(void);
int ram_write_tracking_start(void);
void ram_write_tracking_stop(void);
+void zero_copy_copied(void);
+
#endif
diff --git a/migration/multifd.c b/migration/multifd.c
index 684c014c86..ff19bd4881 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -624,6 +624,8 @@ int multifd_send_sync_main(QEMUFile *f)
if (ret < 0) {
error_report_err(err);
return -1;
+ } else if (ret == 1) {
+ zero_copy_copied();
}
}
}
diff --git a/migration/ram.c b/migration/ram.c
index 01f9cc1d72..0b71993951 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -407,6 +407,11 @@ static void ram_transferred_add(uint64_t bytes)
ram_counters.transferred += bytes;
}
+void zero_copy_copied(void)
+{
+ ram_counters.zero_copy_copied++;
+}
+
/* used by the search for pages to send */
struct PageSearchStatus {
/* Current block being searched */
--
2.36.1
