[v5,12/17] migration: Send the fd number which we are going to use for this page

We are still sending the page through the main channel, that would
change later in the series

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/ram.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

* Juan Quintela (quintela@redhat.com) wrote:
> We are still sending the page through the main channel, that would
> change later in the series
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/ram.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 90e1bcb..ac0742f 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -568,7 +568,7 @@ static int multifd_send_page(uint8_t *address)
>      qemu_mutex_unlock(&p->mutex);
>      qemu_sem_post(&p->sem);
>  
> -    return 0;
> +    return i;

is 'i' anything sane so far - I think this is currently a bogus value
so perhaps it's best to keep it as 0 till later?
Also, add a comment to multifd_send_page to say it'll return the fd
to use.


>  }
>  
>  struct MultiFDRecvParams {
> @@ -1143,6 +1143,7 @@ static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
>                              bool last_stage)
>  {
>      int pages;
> +    uint16_t fd_num;
>      uint8_t *p;
>      RAMBlock *block = pss->block;
>      ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
> @@ -1154,8 +1155,10 @@ static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
>          ram_counters.transferred +=
>              save_page_header(rs, rs->f, block,
>                               offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> +        fd_num = multifd_send_page(p);
> +        qemu_put_be16(rs->f, fd_num);

Check for errors from multifd_send_page?
(I'd have preferred to have made this one field in a new fixed size word
which will get used for other things as well, but I'm OK with it this
way).

I think you've also got a 2^8 fd limit in some of the other configs
as opposed to the 2^16 here.

> +        ram_counters.transferred += 2; /* size of fd_num */
>          qemu_put_buffer(rs->f, p, TARGET_PAGE_SIZE);
> -        multifd_send_page(p);
>          ram_counters.transferred += TARGET_PAGE_SIZE;
>          pages = 1;
>          ram_counters.normal++;
> @@ -2905,6 +2908,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>      while (!postcopy_running && !ret && !(flags & RAM_SAVE_FLAG_EOS)) {
>          ram_addr_t addr, total_ram_bytes;
>          void *host = NULL;
> +        uint16_t fd_num;
>          uint8_t ch;
>  
>          addr = qemu_get_be64(f);
> @@ -3015,6 +3019,11 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>              break;
>  
>          case RAM_SAVE_FLAG_MULTIFD_PAGE:
> +            fd_num = qemu_get_be16(f);
> +            if (fd_num != 0) {
> +                /* this is yet an unused variable, changed later */
> +                fd_num = fd_num;
> +            }
>              qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
>              break;

Dave

> -- 
> 2.9.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

On 17/07/2017 15:42, Juan Quintela wrote:
> We are still sending the page through the main channel, that would
> change later in the series
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/ram.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 90e1bcb..ac0742f 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -568,7 +568,7 @@ static int multifd_send_page(uint8_t *address)
>      qemu_mutex_unlock(&p->mutex);
>      qemu_sem_post(&p->sem);
>  
> -    return 0;
> +    return i;
>  }
>  
>  struct MultiFDRecvParams {
> @@ -1143,6 +1143,7 @@ static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
>                              bool last_stage)
>  {
>      int pages;
> +    uint16_t fd_num;
>      uint8_t *p;
>      RAMBlock *block = pss->block;
>      ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
> @@ -1154,8 +1155,10 @@ static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
>          ram_counters.transferred +=
>              save_page_header(rs, rs->f, block,
>                               offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> +        fd_num = multifd_send_page(p);
> +        qemu_put_be16(rs->f, fd_num);
> +        ram_counters.transferred += 2; /* size of fd_num */
>          qemu_put_buffer(rs->f, p, TARGET_PAGE_SIZE);
> -        multifd_send_page(p);
>          ram_counters.transferred += TARGET_PAGE_SIZE;
>          pages = 1;
>          ram_counters.normal++;
> @@ -2905,6 +2908,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>      while (!postcopy_running && !ret && !(flags & RAM_SAVE_FLAG_EOS)) {
>          ram_addr_t addr, total_ram_bytes;
>          void *host = NULL;
> +        uint16_t fd_num;
>          uint8_t ch;
>  
>          addr = qemu_get_be64(f);
> @@ -3015,6 +3019,11 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>              break;
>  
>          case RAM_SAVE_FLAG_MULTIFD_PAGE:
> +            fd_num = qemu_get_be16(f);
> +            if (fd_num != 0) {
> +                /* this is yet an unused variable, changed later */
> +                fd_num = fd_num;
> +            }
>              qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
>              break;
>  
> 


I'm still not convinced of doing this instead of just treating all
sockets equivalently (and flushing them all when the main socket is told
that there is a new block).

Paolo