Re: [Qemu-devel] [Qemu-stable] [PATCH] migration: disable auto-converge during bulk block migration

[Michael Roth]

Quoting Peter Lieven (2017-09-21 07:32:32)
> 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: address@hidden
> Signed-off-by: Peter Lieven <address@hidden>

FYI: this patch has been tagged for stable 2.10.1, but is not yet
upstream. Patch freeze for 2.10.1 is September 27th.

> ---
>  migration/block.c | 5 +++++
>  migration/block.h | 7 +++++++
>  migration/ram.c   | 3 ++-
>  3 files changed, 14 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..720470e 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 +624,7 @@ static void migration_bitmap_sync(RAMState *rs)
>              / (end_time - rs->time_last_bitmap_sync);
>          bytes_xfer_now = ram_counters.transferred;
> 
> -        if (migrate_auto_converge()) {
> +        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
> -- 
> 1.9.1
> 
>