migration: use dirty_rate_high_cnt more aggressively

The commit message from 070afca25 suggests that dirty_rate_high_cnt
should be used more aggressively to start throttling after two
iterations instead of four. The code, however, only changes the auto
convergence behaviour to throttle after three iterations. This makes the
behaviour more aggressive by kicking off throttling after two iterations
as originally intended.

Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/migration/ram.c b/migration/ram.c
index 1a3d9e6d875220cfbcc65de09725bb7cb5746e1b..26e03a5dfa35bccdebc29d8d3c00313f9e91653e 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -708,7 +708,7 @@ static void migration_bitmap_sync(RAMState *rs)
 
             if ((rs->num_dirty_pages_period * TARGET_PAGE_SIZE >
                    (bytes_xfer_now - rs->bytes_xfer_prev) / 2) &&
-                (rs->dirty_rate_high_cnt++ >= 2)) {
+                (++rs->dirty_rate_high_cnt >= 2)) {
                     trace_migration_throttle();
                     rs->dirty_rate_high_cnt = 0;
                     mig_throttle_guest_down();