Re: [Qemu-devel] [PATCH v10 08/14] migration: Transfer pages over new channels

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

* Juan Quintela (quintela@redhat.com) wrote:
> We switch for sending the page number to send real pages.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>

Yes, I think this one makes sense (and explains some of the earlier
stuff), so


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> --
> 
> Remove the HACK bit, now we have the function that calculates the size
> of a page exported.
> Rename multifd_pages{_now}, to sent pages
> Remove multifd pages field, it is the same than normal pages
> Merge test channels here
> Make sent_pages also work for non multifd case
> ---
>  migration/migration.c | 10 +++++++++-
>  migration/ram.c       | 41 +++++++++++++++++++++++++++++------------
>  2 files changed, 38 insertions(+), 13 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 1545f3a0b0..6ebcfa36cc 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2230,6 +2230,8 @@ static void *migration_thread(void *opaque)
>       */
>      int64_t threshold_size = 0;
>      int64_t qemu_file_bytes = 0;
> +    /* Stores how many pages we have sent */
> +    int64_t sent_pages = 0;
>      int64_t start_time = initial_time;
>      int64_t end_time;
>      bool old_vm_running = false;
> @@ -2318,8 +2320,13 @@ static void *migration_thread(void *opaque)
>          current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
>          if (current_time >= initial_time + BUFFER_DELAY) {
>              uint64_t qemu_file_bytes_now = qemu_ftell(s->to_dst_file);
> +            uint64_t sent_pages_now = ram_counters.normal;
> +            /* multifd sends data out of the qemu_file */
> +            uint64_t multifd_transferred = migrate_use_multifd() ?
> +                (sent_pages_now - sent_pages) * qemu_target_page_size() : 0;
>              uint64_t transferred_bytes =
> -                qemu_file_bytes_now - qemu_file_bytes;
> +                (qemu_file_bytes_now - qemu_file_bytes) +
> +                multifd_transferred;
>              uint64_t time_spent = current_time - initial_time;
>              double bandwidth = (double)transferred_bytes / time_spent;
>              threshold_size = bandwidth * s->parameters.downtime_limit;
> @@ -2339,6 +2346,7 @@ static void *migration_thread(void *opaque)
>              qemu_file_reset_rate_limit(s->to_dst_file);
>              initial_time = current_time;
>              qemu_file_bytes = qemu_file_bytes_now;
> +            sent_pages = sent_pages_now;
>          }
>          if (qemu_file_rate_limit(s->to_dst_file)) {
>              /* usleep expects microseconds */
> diff --git a/migration/ram.c b/migration/ram.c
> index 8443806f12..20f3726909 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -542,12 +542,20 @@ static void *multifd_send_thread(void *opaque)
>              break;
>          }
>          if (p->pages->used) {
> +            Error *local_err = NULL;
> +            size_t ret;
> +            uint32_t used;
> +
> +            used = p->pages->used;
>              p->pages->used = 0;
>              qemu_mutex_unlock(&p->mutex);
>  
> -            trace_multifd_send(p->id, p->pages->seq, p->pages->used);
> -            /* ToDo: send page here */
> -
> +            trace_multifd_send(p->id, p->pages->seq, used);
> +            ret = qio_channel_writev_all(p->c, p->pages->iov, used, &local_err);
> +            if (ret != 0) {
> +                terminate_multifd_send_threads(local_err);
> +                return NULL;
> +            }
>              qemu_mutex_lock(&multifd_send_state->mutex);
>              p->done = true;
>              p->packets_sent++;
> @@ -754,12 +762,21 @@ static void *multifd_recv_thread(void *opaque)
>              break;
>          }
>          if (p->pages->used) {
> +            Error *local_err = NULL;
> +            size_t ret;
> +            uint32_t used;
> +
> +            used = p->pages->used;
>              p->pages->used = 0;
> +            qemu_mutex_unlock(&p->mutex);
>  
> -            trace_multifd_recv(p->id, p->pages->seq, p->pages->used);
> -
> -            /* ToDo: receive pages here */
> -
> +            trace_multifd_recv(p->id, p->pages->seq, used);
> +            ret = qio_channel_readv_all(p->c, p->pages->iov, used, &local_err);
> +            if (ret != 0) {
> +                terminate_multifd_recv_threads(local_err);
> +                return NULL;
> +            }
> +            qemu_mutex_lock(&p->mutex);
>              p->done = true;
>              p->packets_recv++;
>              qemu_mutex_unlock(&p->mutex);
> @@ -1311,12 +1328,9 @@ static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
>  {
>      int pages;
>      uint16_t fd_num;
> -    uint8_t *p;
>      RAMBlock *block = pss->block;
>      ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
>  
> -    p = block->host + offset;
> -
>      pages = save_zero_page(rs, block, offset);
>      if (pages == -1) {
>          ram_counters.transferred +=
> @@ -1325,8 +1339,12 @@ static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
>          fd_num = multifd_send_page(block, offset,
>                                     rs->migration_dirty_pages == 1);
>          qemu_put_be16(rs->f, fd_num);
> +        if (fd_num != MULTIFD_CONTINUE) {
> +            /* We start with a different channel.
> +               Flush pending work */
> +            qemu_fflush(rs->f);
> +        }
>          ram_counters.transferred += 2; /* size of fd_num */
> -        qemu_put_buffer(rs->f, p, TARGET_PAGE_SIZE);
>          ram_counters.transferred += TARGET_PAGE_SIZE;
>          pages = 1;
>          ram_counters.normal++;
> @@ -3278,7 +3296,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>          case RAM_SAVE_FLAG_MULTIFD_PAGE:
>              fd_num = qemu_get_be16(f);
>              multifd_recv_page(block, addr, host, fd_num);
> -            qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
>              break;
>  
>          case RAM_SAVE_FLAG_EOS:
> -- 
> 2.14.3
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK