Re: [Qemu-devel] [v7 10/14] migration: Add the core code for decompression

[Juan Quintela <quintela@redhat.com>]

Liang Li <liang.z.li@intel.com> wrote:
> Implement the core logic of multiple thread decompression,
> the decompression can work now.
>
> Signed-off-by: Liang Li <liang.z.li@intel.com>
> Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
> ---
>  arch_init.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 48 insertions(+), 3 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 8fb2ea4..b88e6b2 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -889,7 +889,6 @@ static inline void start_compression(CompressParam *param)
>      qemu_mutex_unlock(&param->mutex);
>  }
>  
> -
>  static uint64_t bytes_transferred;
>  
>  static void flush_compressed_data(QEMUFile *f)
> @@ -1458,8 +1457,28 @@ void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
>  
>  static void *do_data_decompress(void *opaque)
>  {
> +    DecompressParam *param = opaque;
> +    size_t pagesize;
> +
>      while (true) {
> -        /* To be done */
> +        qemu_mutex_lock(&param->mutex);
> +        while (!param->start && !param->quit) {
> +            qemu_cond_wait(&param->cond, &param->mutex);

We don't check here if we have received a quit


> +            pagesize = TARGET_PAGE_SIZE;
> +            /* uncompress() will return failed in some case, especially
> +             * when the page is dirted when doing the compression, it's
> +             * not a problem because the dirty page will be retransferred
> +             * and uncompress() won't break the data in other pages.
> +             */
> +            uncompress((Bytef *)param->des, &pagesize,
> +                       (const Bytef *)param->compbuf, param->len);
> +            param->start = false;
> +        }
> +        if (param->quit) {
> +            qemu_mutex_unlock(&param->mutex);
> +            break;
> +        }
> +        qemu_mutex_unlock(&param->mutex);
>      }
>  
>      return NULL;
> @@ -1489,6 +1508,12 @@ void migrate_decompress_threads_join(void)
>  
>      thread_count = migrate_decompress_threads();
>      for (i = 0; i < thread_count; i++) {
> +        qemu_mutex_lock(&decomp_param[i].mutex);
> +        decomp_param[i].quit = true;
> +        qemu_cond_signal(&decomp_param[i].cond);

We set quit and send a signal to wakeup the thread, but it will try to
uncompress a page.  Shouldn't we change the position of the param->quit
check for exit?  I think it should be inside the loop.

> +        qemu_mutex_unlock(&decomp_param[i].mutex);
> +    }
> +    for (i = 0; i < thread_count; i++) {
>          qemu_thread_join(decompress_threads + i);
>          qemu_mutex_destroy(&decomp_param[i].mutex);
>          qemu_cond_destroy(&decomp_param[i].cond);
> @@ -1505,7 +1530,27 @@ void migrate_decompress_threads_join(void)
>  static void decompress_data_with_multi_threads(uint8_t *compbuf,
>                                                 void *host, int len)
>  {
> -    /* To be done */
> +    int idx, thread_count;
> +
> +    thread_count = migrate_decompress_threads();
> +    while (true) {
> +        for (idx = 0; idx < thread_count; idx++) {
> +            qemu_mutex_lock(&decomp_param[idx].mutex);
> +            if (!decomp_param[idx].start) {
> +                memcpy(decomp_param[idx].compbuf, compbuf, len);
> +                decomp_param[idx].des = host;
> +                decomp_param[idx].len = len;
> +                decomp_param[idx].start = true;
> +                qemu_cond_signal(&decomp_param[idx].cond);
> +                qemu_mutex_unlock(&decomp_param[idx].mutex);
> +                break;
> +            }
> +            qemu_mutex_unlock(&decomp_param[idx].mutex);
> +        }
> +        if (idx < thread_count) {
> +            break;
> +        }
> +    }
>  }
>  
>  static int ram_load(QEMUFile *f, void *opaque, int version_id)