Re: [Qemu-devel] [PATCH v3 4/5] migration: Convert ram to use new load_setup()/load_cleanup()

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> Once there, I rename ram_migration_cleanup() to ram_save_cleanup().
> Notice that this is the first pass, and I only passed XBZRLE to the
> new scheme.  Moved decoded_buf to inside XBZRLE struct.
> As a bonus, I don't have to export xbzrle functions from ram.c.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>


Note a tiny comment typo below, but other than that:

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> --
> 
> loaded_data pointer was needed because called can change it (dave)
> ---
>  migration/migration.c |  3 ---
>  migration/ram.c       | 49 ++++++++++++++++++++++++++++++++++++-------------
>  migration/ram.h       |  1 -
>  3 files changed, 36 insertions(+), 17 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 520d9b9..aaaf7ff 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -350,9 +350,6 @@ static void process_incoming_migration_co(void *opaque)
>          migrate_decompress_threads_join();
>          exit(EXIT_FAILURE);
>      }
> -
> -    free_xbzrle_decoded_buf();
> -
>      mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
>      qemu_bh_schedule(mis->bh);
>  }
> diff --git a/migration/ram.c b/migration/ram.c
> index 649f76c..a619e0b 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -85,11 +85,10 @@ static struct {
>      QemuMutex lock;
>      /* it will store a page full of zeros */
>      uint8_t *zero_target_page;
> +    /* buffer used for XBZRLE decoding */
> +    uint8_t *decoded_buf;
>  } XBZRLE;
>  
> -/* buffer used for XBZRLE decoding */
> -static uint8_t *xbzrle_decoded_buf;
> -
>  static void XBZRLE_cache_lock(void)
>  {
>      if (migrate_use_xbzrle())
> @@ -1350,13 +1349,18 @@ uint64_t ram_bytes_total(void)
>      return total;
>  }
>  
> -void free_xbzrle_decoded_buf(void)
> +static void xbzrle_load_setup(void)
>  {
> -    g_free(xbzrle_decoded_buf);
> -    xbzrle_decoded_buf = NULL;
> +    XBZRLE.decoded_buf = g_malloc(TARGET_PAGE_SIZE);
>  }
>  
> -static void ram_migration_cleanup(void *opaque)
> +static void xbzrle_load_cleanup(void)
> +{
> +    g_free(XBZRLE.decoded_buf);
> +    XBZRLE.decoded_buf = NULL;
> +}
> +
> +static void ram_save_cleanup(void *opaque)
>  {
>      RAMState **rsp = opaque;
>      RAMBlock *block;
> @@ -2078,11 +2082,6 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
>      int xh_flags;
>      uint8_t *loaded_data;
>  
> -    if (!xbzrle_decoded_buf) {
> -        xbzrle_decoded_buf = g_malloc(TARGET_PAGE_SIZE);
> -    }
> -    loaded_data = xbzrle_decoded_buf;
> -
>      /* extract RLE header */
>      xh_flags = qemu_get_byte(f);
>      xh_len = qemu_get_be16(f);
> @@ -2096,7 +2095,9 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
>          error_report("Failed to load XBZRLE page - len overflow!");
>          return -1;
>      }
> +    loaded_data = XBZRLE.decoded_buf;
>      /* load data and decode */
> +    /* it can change laded_data to point to an internal buffer */
                         ^--- o

>      qemu_get_buffer_in_place(f, &loaded_data, xh_len);
>  
>      /* decode RLE */
> @@ -2310,6 +2311,26 @@ static void decompress_data_with_multi_threads(QEMUFile *f,
>  }
>  
>  /**
> + * ram_load_setup: Setup RAM for migration incoming side
> + *
> + * Returns zero to indicate success and negative for error
> + *
> + * @f: QEMUFile where to receive the data
> + * @opaque: RAMState pointer
> + */
> +static int ram_load_setup(QEMUFile *f, void *opaque)
> +{
> +    xbzrle_load_setup();
> +    return 0;
> +}
> +
> +static int ram_load_cleanup(void *opaque)
> +{
> +    xbzrle_load_cleanup();
> +    return 0;
> +}
> +
> +/**
>   * ram_postcopy_incoming_init: allocate postcopy data structures
>   *
>   * Returns 0 for success and negative if there was one error
> @@ -2629,7 +2650,9 @@ static SaveVMHandlers savevm_ram_handlers = {
>      .save_live_complete_precopy = ram_save_complete,
>      .save_live_pending = ram_save_pending,
>      .load_state = ram_load,
> -    .save_cleanup = ram_migration_cleanup,
> +    .save_cleanup = ram_save_cleanup,
> +    .load_setup = ram_load_setup,
> +    .load_cleanup = ram_load_cleanup,
>  };
>  
>  void ram_mig_init(void)
> diff --git a/migration/ram.h b/migration/ram.h
> index 6272eb0..a8b79a4 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -47,7 +47,6 @@ void migrate_decompress_threads_join(void);
>  uint64_t ram_pagesize_summary(void);
>  int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len);
>  void acct_update_position(QEMUFile *f, size_t size, bool zero);
> -void free_xbzrle_decoded_buf(void);
>  void ram_debug_dump_bitmap(unsigned long *todump, bool expected,
>                             unsigned long pages);
>  void ram_postcopy_migrated_memory_release(MigrationState *ms);
> -- 
> 2.9.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK