Re: [Qemu-devel] [PATCH 10/17] migration: create ram_multifd_page

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

* Juan Quintela (quintela@redhat.com) wrote:
> The function still don't use multifd, but we have simplified
> ram_save_page, xbzrle and RDMA stuff is gone.  We have added a new
> counter and a new flag for this type of pages.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>

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

Dave

> ---
>  hmp.c                         |  2 ++
>  include/migration/migration.h |  1 +
>  migration/migration.c         |  1 +
>  migration/ram.c               | 51 ++++++++++++++++++++++++++++++++++++++++++-
>  qapi-schema.json              |  4 +++-
>  5 files changed, 57 insertions(+), 2 deletions(-)
> 
> diff --git a/hmp.c b/hmp.c
> index e579766..76bc8c7 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -222,6 +222,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
>              monitor_printf(mon, "postcopy request count: %" PRIu64 "\n",
>                             info->ram->postcopy_requests);
>          }
> +        monitor_printf(mon, "multifd: %" PRIu64 " pages\n",
> +                       info->ram->multifd);
>      }
> 
>      if (info->has_disk) {
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 3989bd6..b3e4f31 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -282,6 +282,7 @@ uint64_t xbzrle_mig_pages_transferred(void);
>  uint64_t xbzrle_mig_pages_overflow(void);
>  uint64_t xbzrle_mig_pages_cache_miss(void);
>  double xbzrle_mig_cache_miss_rate(void);
> +uint64_t multifd_mig_pages_transferred(void);
> 
>  void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
>  void ram_debug_dump_bitmap(unsigned long *todump, bool expected);
> diff --git a/migration/migration.c b/migration/migration.c
> index ab48f06..1d62b91 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -652,6 +652,7 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
>      info->ram->mbps = s->mbps;
>      info->ram->dirty_sync_count = s->dirty_sync_count;
>      info->ram->postcopy_requests = s->postcopy_requests;
> +    info->ram->multifd = multifd_mig_pages_transferred();
> 
>      if (s->state != MIGRATION_STATUS_COMPLETED) {
>          info->ram->remaining = ram_bytes_remaining();
> diff --git a/migration/ram.c b/migration/ram.c
> index 5ad7cb3..c71929e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -61,6 +61,7 @@ static uint64_t bitmap_sync_count;
>  #define RAM_SAVE_FLAG_XBZRLE   0x40
>  /* 0x80 is reserved in migration.h start with 0x100 next */
>  #define RAM_SAVE_FLAG_COMPRESS_PAGE    0x100
> +#define RAM_SAVE_FLAG_MULTIFD_PAGE     0x200
> 
>  static uint8_t *ZERO_TARGET_PAGE;
> 
> @@ -141,6 +142,7 @@ typedef struct AccountingInfo {
>      uint64_t dup_pages;
>      uint64_t skipped_pages;
>      uint64_t norm_pages;
> +    uint64_t multifd_pages;
>      uint64_t iterations;
>      uint64_t xbzrle_bytes;
>      uint64_t xbzrle_pages;
> @@ -211,6 +213,11 @@ uint64_t xbzrle_mig_pages_overflow(void)
>      return acct_info.xbzrle_overflows;
>  }
> 
> +uint64_t multifd_mig_pages_transferred(void)
> +{
> +    return acct_info.multifd_pages;
> +}
> +
>  /* This is the last block that we have visited serching for dirty pages
>   */
>  static RAMBlock *last_seen_block;
> @@ -990,6 +997,33 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus *pss,
>      return pages;
>  }
> 
> +static int ram_multifd_page(QEMUFile *f, PageSearchStatus *pss,
> +                            bool last_stage, uint64_t *bytes_transferred)
> +{
> +    int pages;
> +    uint8_t *p;
> +    RAMBlock *block = pss->block;
> +    ram_addr_t offset = pss->offset;
> +
> +    p = block->host + offset;
> +
> +    if (block == last_sent_block) {
> +        offset |= RAM_SAVE_FLAG_CONTINUE;
> +    }
> +    pages = save_zero_page(f, block, offset, p, bytes_transferred);
> +    if (pages == -1) {
> +        *bytes_transferred +=
> +            save_page_header(f, block, offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> +        qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
> +        *bytes_transferred += TARGET_PAGE_SIZE;
> +        pages = 1;
> +        acct_info.norm_pages++;
> +        acct_info.multifd_pages++;
> +    }
> +
> +    return pages;
> +}
> +
>  static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
>                                  ram_addr_t offset)
>  {
> @@ -1427,6 +1461,8 @@ static int ram_save_target_page(MigrationState *ms, QEMUFile *f,
>              res = ram_save_compressed_page(f, pss,
>                                             last_stage,
>                                             bytes_transferred);
> +        } else if (migrate_use_multifd()) {
> +            res = ram_multifd_page(f, pss, last_stage, bytes_transferred);
>          } else {
>              res = ram_save_page(f, pss, last_stage,
>                                  bytes_transferred);
> @@ -2678,6 +2714,10 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>      if (!migrate_use_compression()) {
>          invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE;
>      }
> +
> +    if (!migrate_use_multifd()) {
> +        invalid_flags |= RAM_SAVE_FLAG_MULTIFD_PAGE;
> +    }
>      /* This RCU critical section can be very long running.
>       * When RCU reclaims in the code start to become numerous,
>       * it will be necessary to reduce the granularity of this
> @@ -2705,13 +2745,17 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>              if (flags & invalid_flags  & RAM_SAVE_FLAG_COMPRESS_PAGE) {
>                  error_report("Received an unexpected compressed page");
>              }
> +            if (flags & invalid_flags  & RAM_SAVE_FLAG_MULTIFD_PAGE) {
> +                error_report("Received an unexpected multifd page");
> +            }
> 
>              ret = -EINVAL;
>              break;
>          }
> 
>          if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE |
> -                     RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
> +                     RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE |
> +                     RAM_SAVE_FLAG_MULTIFD_PAGE)) {
>              RAMBlock *block = ram_block_from_stream(f, flags);
> 
>              host = host_from_ram_block_offset(block, addr);
> @@ -2786,6 +2830,11 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>                  break;
>              }
>              break;
> +
> +        case RAM_SAVE_FLAG_MULTIFD_PAGE:
> +            qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
> +            break;
> +
>          case RAM_SAVE_FLAG_EOS:
>              /* normal exit */
>              break;
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 54232ee..3e93f7f 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -574,6 +574,7 @@
>  #
>  # @postcopy-requests: The number of page requests received from the destination
>  #        (since 2.7)
> +# @multifd: number of pages sent with multifd (since 2.9)
>  #
>  # Since: 0.14.0
>  ##
> @@ -582,7 +583,8 @@
>             'duplicate': 'int', 'skipped': 'int', 'normal': 'int',
>             'normal-bytes': 'int', 'dirty-pages-rate' : 'int',
>             'mbps' : 'number', 'dirty-sync-count' : 'int',
> -           'postcopy-requests' : 'int' } }
> +           'postcopy-requests' : 'int',
> +           'multifd' : 'int'} }
> 
>  ##
>  # @XBZRLECacheStats:
> -- 
> 2.9.3
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK