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 dirty_sync_missed_zero_copy migration stat to let the user know
about it.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Message-Id: <
20220711211112.18951-4-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
if (ret < 0) {
error_report_err(err);
return -1;
+ } else if (ret == 1) {
+ dirty_sync_missed_zero_copy();
}
}
}
ram_counters.transferred += bytes;
}
+void dirty_sync_missed_zero_copy(void)
+{
+ ram_counters.dirty_sync_missed_zero_copy++;
+}
+
/* used by the search for pages to send */
struct PageSearchStatus {
/* Current block being searched */
int ram_write_tracking_start(void);
void ram_write_tracking_stop(void);
+void dirty_sync_missed_zero_copy(void);
+
#endif