Re: [Qemu-devel] [RFC PATCH v2 02/12] mc: timestamp migration_bitmap and KVM logdirty usage

[Juan Quintela]

address@hidden wrote:
> From: "Michael R. Hines" <address@hidden>
>
> We also later export these statistics over QMP for better
> monitoring of micro-checkpointing as the workload changes.
>
> Signed-off-by: Michael R. Hines <address@hidden>
> ---
>  arch_init.c | 34 ++++++++++++++++++++++++++++------
>  1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 80574a0..b8364b0 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -193,6 +193,8 @@ typedef struct AccountingInfo {
>      uint64_t skipped_pages;
>      uint64_t norm_pages;
>      uint64_t iterations;
> +    uint64_t log_dirty_time;
> +    uint64_t migration_bitmap_time;
>      uint64_t xbzrle_bytes;
>      uint64_t xbzrle_pages;
>      uint64_t xbzrle_cache_miss;
> @@ -201,7 +203,7 @@ typedef struct AccountingInfo {
>  
>  static AccountingInfo acct_info;
>  
> -static void acct_clear(void)
> +void acct_clear(void)
>  {
>      memset(&acct_info, 0, sizeof(acct_info));
>  }
> @@ -236,6 +238,16 @@ uint64_t norm_mig_pages_transferred(void)
>      return acct_info.norm_pages;
>  }
>  
> +uint64_t norm_mig_log_dirty_time(void)
> +{
> +    return acct_info.log_dirty_time;
> +}
> +
> +uint64_t norm_mig_bitmap_time(void)
> +{
> +    return acct_info.migration_bitmap_time;
> +}
> +
>  uint64_t xbzrle_mig_bytes_transferred(void)
>  {
>      return acct_info.xbzrle_bytes;
> @@ -426,27 +438,35 @@ static void migration_bitmap_sync(void)
>      static int64_t num_dirty_pages_period;
>      int64_t end_time;
>      int64_t bytes_xfer_now;
> +    int64_t begin_time;
> +    int64_t dirty_time;
>  
>      if (!bytes_xfer_prev) {
>          bytes_xfer_prev = ram_bytes_transferred();
>      }
>  
> +    begin_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
>      if (!start_time) {
>          start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
>      }

     if (!start_time) {
         start_time = begin_time;
     }

Althought I think we need to search for better names?

start_time --> migration_start_time
begin_time --> iteration_start_time
?

I am open to better names.

> -
>      trace_migration_bitmap_sync_start();
>      address_space_sync_dirty_bitmap(&address_space_memory);
>  
> +    dirty_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> +
>      QTAILQ_FOREACH(block, &ram_list.blocks, next) {
>          migration_bitmap_sync_range(block->mr->ram_addr, block->length);
>      }
> +
>      trace_migration_bitmap_sync_end(migration_dirty_pages
>                                      - num_dirty_pages_init);
>      num_dirty_pages_period += migration_dirty_pages - num_dirty_pages_init;
>      end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
>  
> -    /* more than 1 second = 1000 millisecons */
> +    acct_info.log_dirty_time += dirty_time - begin_time;
> +    acct_info.migration_bitmap_time += end_time - dirty_time;
> +
> +    /* more than 1 second = 1000 milliseconds */
>      if (end_time > start_time + 1000) {
>          if (migrate_auto_converge()) {
>              /* The following detection logic can be refined later. For now:
> @@ -548,9 +568,11 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
>              /* XBZRLE overflow or normal page */
>              if (bytes_sent == -1) {
>                  bytes_sent = save_block_hdr(f, block, offset, cont, 
> RAM_SAVE_FLAG_PAGE);
> -                qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
> -                bytes_sent += TARGET_PAGE_SIZE;
> -                acct_info.norm_pages++;
> +                if (ret != RAM_SAVE_CONTROL_DELAYED) {
> +                    qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
> +                    bytes_sent += TARGET_PAGE_SIZE;
> +                    acct_info.norm_pages++;
> +                }
>              }
>  
>              /* if page is unmodified, continue to the next */

Except for this bit, rest of the patch ok.