[Xen-changelog] [qemu-xen master] migration: disable auto-converge during bulk block migration

[patchbot@xxxxxxx]

commit 547435f5506e351baa2151a681eeaca2cae79591
Author:     Peter Lieven <pl@xxxxxxx>
AuthorDate: Tue Sep 26 12:33:16 2017 +0200
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu Sep 28 16:55:44 2017 -0500

    migration: disable auto-converge during bulk block migration
    
    auto-converge and block migration currently do not play well together.
    During block migration the auto-converge logic detects that ram
    migration makes no progress and thus throttles down the vm until
    it nearly stalls completely. Avoid this by disabling the throttling
    logic during the bulk phase of the block migration.
    
    Cc: qemu-stable@xxxxxxxxxx
    Signed-off-by: Peter Lieven <pl@xxxxxxx>
    Message-Id: <1506421996-12513-1-git-send-email-pl@xxxxxxx>
    Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
    Reviewed-by: Juan Quintela <quintela@xxxxxxxxxx>
    Signed-off-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
    (cherry picked from commit 9ac78b6171bec47083a9b6ce88dc1f114caea2f9)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 migration/block.c | 5 +++++
 migration/block.h | 7 +++++++
 migration/ram.c   | 6 +++++-
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/migration/block.c b/migration/block.c
index 9171f60..606ad4d 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -161,6 +161,11 @@ int blk_mig_active(void)
     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 }
 
+int blk_mig_bulk_active(void)
+{
+    return blk_mig_active() && !block_mig_state.bulk_completed;
+}
+
 uint64_t blk_mig_bytes_transferred(void)
 {
     BlkMigDevState *bmds;
diff --git a/migration/block.h b/migration/block.h
index 22ebe94..3178609 100644
--- a/migration/block.h
+++ b/migration/block.h
@@ -16,6 +16,7 @@
 
 #ifdef CONFIG_LIVE_BLOCK_MIGRATION
 int blk_mig_active(void);
+int blk_mig_bulk_active(void);
 uint64_t blk_mig_bytes_transferred(void);
 uint64_t blk_mig_bytes_remaining(void);
 uint64_t blk_mig_bytes_total(void);
@@ -25,6 +26,12 @@ static inline int blk_mig_active(void)
 {
     return false;
 }
+
+static inline int blk_mig_bulk_active(void)
+{
+    return false;
+}
+
 static inline uint64_t blk_mig_bytes_transferred(void)
 {
     return 0;
diff --git a/migration/ram.c b/migration/ram.c
index e18b3e2..576e100 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -46,6 +46,7 @@
 #include "exec/ram_addr.h"
 #include "qemu/rcu_queue.h"
 #include "migration/colo.h"
+#include "migration/block.h"
 
 /***********************************************************/
 /* ram save/restore */
@@ -623,7 +624,10 @@ static void migration_bitmap_sync(RAMState *rs)
             / (end_time - rs->time_last_bitmap_sync);
         bytes_xfer_now = ram_counters.transferred;
 
-        if (migrate_auto_converge()) {
+        /* During block migration the auto-converge logic incorrectly detects
+         * that ram migration makes no progress. Avoid this by disabling the
+         * throttling logic during the bulk phase of block migration. */
+        if (migrate_auto_converge() && !blk_mig_bulk_active()) {
             /* The following detection logic can be refined later. For now:
                Check to see if the dirtied bytes is 50% more than the approx.
                amount of bytes that just got transferred since the last time we
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master

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