Re: [Qemu-devel] [v3 05/13] arch_init: alloc and free data struct in multi-thread compression

[Dr. David Alan Gilbert]

* Liang Li (address@hidden) wrote:
> Define the data structure and varibles used when doing multiple
> thread compression, and add the code to initialize and free them.
> 
> Signed-off-by: Liang Li <address@hidden>
> Signed-off-by: Yang Zhang <address@hidden>
> ---
>  arch_init.c | 34 +++++++++++++++++++++++++++++++++-
>  1 file changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/arch_init.c b/arch_init.c
> index 2f1d0c4..f21a8ea 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -340,16 +340,29 @@ static bool ram_bulk_stage;
>  #define COMPRESS_BUF_SIZE (TARGET_PAGE_SIZE + 16)
>  
>  struct compress_param {
> -    /* To be done */
> +    int state;
> +    QEMUFile *file;
> +    QemuMutex mutex;
> +    QemuCond cond;
> +    RAMBlock *block;
> +    ram_addr_t offset;
>  };
>  typedef struct compress_param compress_param;
>  
> +enum {
> +    DONE,
> +    START,
> +};
> +

Do you really need any more than a 'bool busy' ?

>  struct decompress_param {
>      /* To be done */
>  };
>  typedef struct decompress_param decompress_param;
>  
>  static compress_param *comp_param;
> +static QemuMutex *mutex;
> +static QemuCond *cond;

Those need better names and a comment; If I'm reading it
correctly, this cond is used to wake up the parent thread
when one of the workers has finished it's task?

> +static QEMUFileOps *empty_ops;
>  static bool quit_thread;
>  static decompress_param *decomp_param;
>  static QemuThread *decompress_threads;
> @@ -381,11 +394,22 @@ void migrate_compress_threads_join(MigrationState *s)
>      thread_count = migrate_compress_threads();
>      for (i = 0; i < thread_count; i++) {
>          qemu_thread_join(s->compress_thread + i);
> +        qemu_fclose(comp_param[i].file);
> +        qemu_mutex_destroy(&comp_param[i].mutex);
> +        qemu_cond_destroy(&comp_param[i].cond);
>      }
> +    qemu_mutex_destroy(mutex);
> +    qemu_cond_destroy(cond);
>      g_free(s->compress_thread);
>      g_free(comp_param);
> +    g_free(cond);
> +    g_free(mutex);
> +    g_free(empty_ops);
>      s->compress_thread = NULL;
>      comp_param = NULL;
> +    cond = NULL;
> +    mutex = NULL;
> +    empty_ops = NULL;
>  }
>  
>  void migrate_compress_threads_create(MigrationState *s)
> @@ -400,7 +424,15 @@ void migrate_compress_threads_create(MigrationState *s)
>      s->compress_thread = g_malloc0(sizeof(QemuThread)
>          * thread_count);
>      comp_param = g_malloc0(sizeof(compress_param) * thread_count);
> +    cond = g_malloc0(sizeof(QemuCond));
> +    mutex = g_malloc0(sizeof(QemuMutex));
> +    empty_ops = g_malloc0(sizeof(QEMUFileOps));

Again this needs to go with the explanation of what you're using
the special QEMUFile for; but I don't think anything outside of
QEMUFile should be allocating a QEMUFileOps (It could be static anyway
rather than malloc'd).  I think you could make empty_ops declared
static in qemu-file.c

> +    qemu_cond_init(cond);
> +    qemu_mutex_init(mutex);
>      for (i = 0; i < thread_count; i++) {
> +        comp_param[i].file = qemu_fopen_ops(NULL, empty_ops);
> +        qemu_mutex_init(&comp_param[i].mutex);
> +        qemu_cond_init(&comp_param[i].cond);
>          qemu_thread_create(s->compress_thread + i, "compress",
>              do_data_compress, comp_param + i, QEMU_THREAD_JOINABLE);
>  
> -- 
> 1.8.3.1
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK