Re: [Qemu-devel] [PATCH v3 7/8] multifd: Add zlib compression support

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

* Juan Quintela (quintela@redhat.com) wrote:
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev-properties.c |  2 +-
>  migration/migration.c     |  9 ++++++++
>  migration/migration.h     |  1 +
>  migration/ram.c           | 47 +++++++++++++++++++++++++++++++++++++++
>  qapi/migration.json       |  2 +-
>  tests/migration-test.c    |  6 +++++
>  6 files changed, 65 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index ebeeb5c88d..e40aa806e2 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -651,7 +651,7 @@ const PropertyInfo qdev_prop_fdc_drive_type = {
>  const PropertyInfo qdev_prop_multifd_compress = {
>      .name = "MultifdCompress",
>      .description = "multifd_compress values, "
> -                   "none",
> +                   "none/zlib",
>      .enum_table = &MultifdCompress_lookup,
>      .get = get_enum,
>      .set = set_enum,
> diff --git a/migration/migration.c b/migration/migration.c
> index d6f8ef342a..69d85cbe5e 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2141,6 +2141,15 @@ bool migrate_use_multifd(void)
>      return s->enabled_capabilities[MIGRATION_CAPABILITY_MULTIFD];
>  }
>  
> +bool migrate_use_multifd_zlib(void)
> +{
> +    MigrationState *s;
> +
> +    s = migrate_get_current();
> +
> +    return s->parameters.multifd_compress == MULTIFD_COMPRESS_ZLIB;
> +}
> +
>  bool migrate_pause_before_switchover(void)
>  {
>      MigrationState *s;
> diff --git a/migration/migration.h b/migration/migration.h
> index 438f17edad..fc4fb841d4 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -269,6 +269,7 @@ bool migrate_ignore_shared(void);
>  
>  bool migrate_auto_converge(void);
>  bool migrate_use_multifd(void);
> +bool migrate_use_multifd_zlib(void);
>  bool migrate_pause_before_switchover(void);
>  int migrate_multifd_channels(void);
>  
> diff --git a/migration/ram.c b/migration/ram.c
> index 6679e4f213..fdb5bf07a5 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -582,6 +582,7 @@ exit:
>  #define MULTIFD_VERSION 1
>  
>  #define MULTIFD_FLAG_SYNC (1 << 0)
> +#define MULTIFD_FLAG_ZLIB (1 << 1)
>  
>  /* This value needs to be a multiple of qemu_target_page_size() */
>  #define MULTIFD_PACKET_SIZE (512 * 1024)
> @@ -663,6 +664,12 @@ typedef struct {
>      uint64_t num_pages;
>      /* syncs main thread and channels */
>      QemuSemaphore sem_sync;
> +    /* stream for compression */
> +    z_stream zs;
> +    /* compressed buffer */
> +    uint8_t *zbuff;
> +    /* size of compressed buffer */
> +    uint32_t zbuff_len;

Does this set need to be in a union or something so that you select
them for different compression types?

>  }  MultiFDSendParams;
>  
>  typedef struct {
> @@ -698,6 +705,12 @@ typedef struct {
>      uint64_t num_pages;
>      /* syncs main thread and channels */
>      QemuSemaphore sem_sync;
> +    /* stream for compression */

de-compression?

> +    z_stream zs;
> +    /* compressed buffer */
> +    uint8_t *zbuff;
> +    /* size of compressed buffer */
> +    uint32_t zbuff_len;
>  } MultiFDRecvParams;
>  
>  typedef struct {
> @@ -1071,6 +1084,9 @@ void multifd_save_cleanup(void)
>          p->packet_len = 0;
>          g_free(p->packet);
>          p->packet = NULL;
> +        deflateEnd(&p->zs);
> +        g_free(p->zbuff);
> +        p->zbuff = NULL;
>      }
>      qemu_sem_destroy(&multifd_send_state->channels_ready);
>      qemu_sem_destroy(&multifd_send_state->sem_sync);
> @@ -1240,6 +1256,7 @@ int multifd_save_setup(void)
>  
>      for (i = 0; i < thread_count; i++) {
>          MultiFDSendParams *p = &multifd_send_state->params[i];
> +        z_stream *zs = &p->zs;
>  
>          qemu_mutex_init(&p->mutex);
>          qemu_sem_init(&p->sem, 0);
> @@ -1253,6 +1270,17 @@ int multifd_save_setup(void)
>          p->packet = g_malloc0(p->packet_len);
>          p->name = g_strdup_printf("multifdsend_%d", i);
>          socket_send_channel_create(multifd_new_send_channel_async, p);
> +        zs->zalloc = Z_NULL;
> +        zs->zfree = Z_NULL;
> +        zs->opaque = Z_NULL;
> +        if (deflateInit(zs, migrate_compress_level()) != Z_OK) {
> +            printf("deflate init failed\n");
> +            return -1;
> +        }
> +        /* We will never have more than page_count pages */
> +        p->zbuff_len = page_count * qemu_target_page_size();
> +        p->zbuff_len *= 2;

Should the ops gain a 'save_init' and 'load_init' so that you can
only do this lot if the compression is enabled?

> +        p->zbuff = g_malloc0(p->zbuff_len);

I'd prefer g_try_malloc and do failure given it's not a tiny buffer.

>      }
>      return 0;
>  }
> @@ -1322,6 +1350,9 @@ int multifd_load_cleanup(Error **errp)
>          p->packet_len = 0;
>          g_free(p->packet);
>          p->packet = NULL;
> +        inflateEnd(&p->zs);
> +        g_free(p->zbuff);
> +        p->zbuff = NULL;
>      }
>      qemu_sem_destroy(&multifd_recv_state->sem_sync);
>      g_free(multifd_recv_state->params);
> @@ -1440,6 +1471,7 @@ int multifd_load_setup(void)
>  
>      for (i = 0; i < thread_count; i++) {
>          MultiFDRecvParams *p = &multifd_recv_state->params[i];
> +        z_stream *zs = &p->zs;
>  
>          qemu_mutex_init(&p->mutex);
>          qemu_sem_init(&p->sem_sync, 0);
> @@ -1449,6 +1481,21 @@ int multifd_load_setup(void)
>                        + sizeof(ram_addr_t) * page_count;
>          p->packet = g_malloc0(p->packet_len);
>          p->name = g_strdup_printf("multifdrecv_%d", i);
> +
> +        zs->zalloc = Z_NULL;
> +        zs->zfree = Z_NULL;
> +        zs->opaque = Z_NULL;
> +        zs->avail_in = 0;
> +        zs->next_in = Z_NULL;
> +        if (inflateInit(zs) != Z_OK) {
> +            printf("inflate init failed\n");
> +            return -1;
> +        }
> +        /* We will never have more than page_count pages */
> +        p->zbuff_len = page_count * qemu_target_page_size();
> +        /* We know compression "could" use more space */
> +        p->zbuff_len *= 2;
> +        p->zbuff = g_malloc0(p->zbuff_len);
>      }
>      return 0;
>  }
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 8ec1944b7a..e6c27fae06 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -493,7 +493,7 @@
>  #
>  ##
>  { 'enum': 'MultifdCompress',
> -  'data': [ 'none' ] }
> +  'data': [ 'none', 'zlib' ] }
>  
>  ##
>  # @MigrationParameter:
> diff --git a/tests/migration-test.c b/tests/migration-test.c
> index 8a1ccc2516..2dd4d4c5b4 100644
> --- a/tests/migration-test.c
> +++ b/tests/migration-test.c
> @@ -1119,6 +1119,11 @@ static void test_multifd_tcp_none(void)
>      test_multifd_tcp("none");
>  }
>  
> +static void test_multifd_tcp_zlib(void)
> +{
> +    test_multifd_tcp("zlib");
> +}
> +
>  int main(int argc, char **argv)
>  {
>      char template[] = "/tmp/migration-test-XXXXXX";
> @@ -1174,6 +1179,7 @@ int main(int argc, char **argv)
>      /* qtest_add_func("/migration/ignore_shared", test_ignore_shared); */
>      qtest_add_func("/migration/xbzrle/unix", test_xbzrle_unix);
>      qtest_add_func("/migration/multifd/tcp/none", test_multifd_tcp_none);
> +    qtest_add_func("/migration/multifd/tcp/zlib", test_multifd_tcp_zlib);
>  
>      ret = g_test_run();
>  
> -- 
> 2.21.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK