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

[Li, Liang Z]

> > @@ -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.

Yes, you are right. if (param->quit)  should be put in front of uncompress().
 I will change it in the final version. (I really hope the next version is the 
final version :) )