Re: [PATCH v3 03/23] multifd: Rename used field to num

[Zheng Chuan]

Hi, Juan,

Sorry, forget to send to qemu-devel, resend it.

On 2021/11/24 18:05, Juan Quintela wrote:
> We will need to split it later in zero_num (number of zero pages) and
> normal_num (number of normal pages).  This name is better.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/multifd.h |  2 +-
>  migration/multifd.c | 38 +++++++++++++++++++-------------------
>  2 files changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/migration/multifd.h b/migration/multifd.h
> index 15c50ca0b2..86820dd028 100644
> --- a/migration/multifd.h
> +++ b/migration/multifd.h
> @@ -55,7 +55,7 @@ typedef struct {
>  
>  typedef struct {
>      /* number of used pages */
> -    uint32_t used;
> +    uint32_t num;
>      /* number of allocated pages */
>      uint32_t allocated;
>      /* global number of generated multifd packets */
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 8125d0015c..8ea86d81dc 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -252,7 +252,7 @@ static MultiFDPages_t *multifd_pages_init(size_t size)
>  
>  static void multifd_pages_clear(MultiFDPages_t *pages)
>  {
> -    pages->used = 0;
> +    pages->num = 0;
>      pages->allocated = 0;
>      pages->packet_num = 0;
>      pages->block = NULL;
> @@ -270,7 +270,7 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
>  
>      packet->flags = cpu_to_be32(p->flags);
>      packet->pages_alloc = cpu_to_be32(p->pages->allocated);
> -    packet->pages_used = cpu_to_be32(p->pages->used);
> +    packet->pages_used = cpu_to_be32(p->pages->num);
>      packet->next_packet_size = cpu_to_be32(p->next_packet_size);
>      packet->packet_num = cpu_to_be64(p->packet_num);
>  
> @@ -278,7 +278,7 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
>          strncpy(packet->ramblock, p->pages->block->idstr, 256);
>      }
>  
> -    for (i = 0; i < p->pages->used; i++) {
> +    for (i = 0; i < p->pages->num; i++) {
>          /* there are architectures where ram_addr_t is 32 bit */
>          uint64_t temp = p->pages->offset[i];
>  
> @@ -332,18 +332,18 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams 
> *p, Error **errp)
>          p->pages = multifd_pages_init(packet->pages_alloc);
>      }
>  
> -    p->pages->used = be32_to_cpu(packet->pages_used);
> -    if (p->pages->used > packet->pages_alloc) {
> +    p->pages->num = be32_to_cpu(packet->pages_used);
> +    if (p->pages->num > packet->pages_alloc) {
>          error_setg(errp, "multifd: received packet "
>                     "with %d pages and expected maximum pages are %d",
> -                   p->pages->used, packet->pages_alloc) ;
> +                   p->pages->num, packet->pages_alloc) ;
>          return -1;
>      }
>  
>      p->next_packet_size = be32_to_cpu(packet->next_packet_size);
>      p->packet_num = be64_to_cpu(packet->packet_num);
>  
> -    if (p->pages->used == 0) {
> +    if (p->pages->num == 0) {
>          return 0;
>      }
>  
> @@ -356,7 +356,7 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams 
> *p, Error **errp)
>          return -1;
>      }
>  
> -    for (i = 0; i < p->pages->used; i++) {
> +    for (i = 0; i < p->pages->num; i++) {
>          uint64_t offset = be64_to_cpu(packet->offset[i]);
>  
>          if (offset > (block->used_length - page_size)) {
> @@ -443,13 +443,13 @@ static int multifd_send_pages(QEMUFile *f)
>          }
>          qemu_mutex_unlock(&p->mutex);
>      }
> -    assert(!p->pages->used);
> +    assert(!p->pages->num);
>      assert(!p->pages->block);
>  
>      p->packet_num = multifd_send_state->packet_num++;
>      multifd_send_state->pages = p->pages;
>      p->pages = pages;
> -    transferred = ((uint64_t) pages->used) * qemu_target_page_size()
> +    transferred = ((uint64_t) pages->num) * qemu_target_page_size()
>                  + p->packet_len;
The size of zero page should not regard as the whole pagesize.
I think the transferred should be updated after you introduce zero_num in 
following patches, such as:
+    transferred = ((uint64_t) p->normal_num) * qemu_target_page_size()
+               + ((uint64_t) p->zero_num) * sizeof(uint64_t);
Otherwise, migration time will get worse if we have low bandwidth limit 
parameter.

I tested it with bandwidth limit of 100MB/s and it works fine:)

>      qemu_file_update_transfer(f, transferred);
>      ram_counters.multifd_bytes += transferred;
> @@ -469,12 +469,12 @@ int multifd_queue_page(QEMUFile *f, RAMBlock *block, 
> ram_addr_t offset)
>      }
>  
>      if (pages->block == block) {
> -        pages->offset[pages->used] = offset;
> -        pages->iov[pages->used].iov_base = block->host + offset;
> -        pages->iov[pages->used].iov_len = qemu_target_page_size();
> -        pages->used++;
> +        pages->offset[pages->num] = offset;
> +        pages->iov[pages->num].iov_base = block->host + offset;
> +        pages->iov[pages->num].iov_len = qemu_target_page_size();
> +        pages->num++;
>  
> -        if (pages->used < pages->allocated) {
> +        if (pages->num < pages->allocated) {
>              return 1;
>          }
>      }
> @@ -586,7 +586,7 @@ void multifd_send_sync_main(QEMUFile *f)
>      if (!migrate_use_multifd()) {
>          return;
>      }
> -    if (multifd_send_state->pages->used) {
> +    if (multifd_send_state->pages->num) {
>          if (multifd_send_pages(f) < 0) {
>              error_report("%s: multifd_send_pages fail", __func__);
>              return;
> @@ -649,7 +649,7 @@ static void *multifd_send_thread(void *opaque)
>          qemu_mutex_lock(&p->mutex);
>  
>          if (p->pending_job) {
> -            uint32_t used = p->pages->used;
> +            uint32_t used = p->pages->num;
>              uint64_t packet_num = p->packet_num;
>              flags = p->flags;
>  
> @@ -665,7 +665,7 @@ static void *multifd_send_thread(void *opaque)
>              p->flags = 0;
>              p->num_packets++;
>              p->num_pages += used;
> -            p->pages->used = 0;
> +            p->pages->num = 0;
>              p->pages->block = NULL;
>              qemu_mutex_unlock(&p->mutex);
>  
> @@ -1091,7 +1091,7 @@ static void *multifd_recv_thread(void *opaque)
>              break;
>          }
>  
> -        used = p->pages->used;
> +        used = p->pages->num;
>          flags = p->flags;
>          /* recv methods don't know how to handle the SYNC flag */
>          p->flags &= ~MULTIFD_FLAG_SYNC;
> 

-- 
Regards.
Chuan