Re: [Qemu-devel] [PATCH v3 3/8] multifd: Create new next_packet_size field

[Dr. David Alan Gilbert]

* Juan Quintela (address@hidden) wrote:
> We need to send this field when we add compression support.  As we are
> still on x- stage, we can do this kind of changes.
> 
> Signed-off-by: Juan Quintela <address@hidden>

OK, so that kind of makes sense - in that what you want to do is read
the whole compressed chunk in one go.

Consider it might be a good idea to add some spare entries here;
say a uint64_t dummy[4] so that if you need any more fields in the
future it'll be easy to add them without breaking compatibility.


Reviewed-by: Dr. David Alan Gilbert <address@hidden>

> ---
>  migration/ram.c        | 15 +++++++++++++--
>  migration/trace-events |  4 ++--
>  2 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 29f0d431a8..26ed26fc2d 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -534,6 +534,8 @@ typedef struct {
>      /* maximum number of allocated pages */
>      uint32_t pages_alloc;
>      uint32_t pages_used;
> +    /* size of the next packet that contains pages */
> +    uint32_t next_packet_size;
>      uint64_t packet_num;
>      char ramblock[256];
>      uint64_t offset[];
> @@ -581,6 +583,8 @@ typedef struct {
>      MultiFDPacket_t *packet;
>      /* multifd flags for each packet */
>      uint32_t flags;
> +    /* size of the next packet that contains pages */
> +    uint32_t next_packet_size;
>      /* global number of generated multifd packets */
>      uint64_t packet_num;
>      /* thread local variables */
> @@ -617,6 +621,8 @@ typedef struct {
>      /* global number of generated multifd packets */
>      uint64_t packet_num;
>      /* thread local variables */
> +    /* size of the next packet that contains pages */
> +    uint32_t next_packet_size;
>      /* packets sent through this channel */
>      uint64_t num_packets;
>      /* pages sent through this channel */
> @@ -721,6 +727,7 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
>      packet->flags = cpu_to_be32(p->flags);
>      packet->pages_alloc = cpu_to_be32(migrate_multifd_page_count());
>      packet->pages_used = cpu_to_be32(p->pages->used);
> +    packet->next_packet_size = cpu_to_be32(p->next_packet_size);
>      packet->packet_num = cpu_to_be64(p->packet_num);
>  
>      if (p->pages->block) {
> @@ -772,6 +779,7 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams 
> *p, Error **errp)
>          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) {
> @@ -1011,6 +1019,7 @@ static void *multifd_send_thread(void *opaque)
>              uint64_t packet_num = p->packet_num;
>              uint32_t flags = p->flags;
>  
> +            p->next_packet_size = used * qemu_target_page_size();
>              multifd_send_fill_packet(p);
>              p->flags = 0;
>              p->num_packets++;
> @@ -1018,7 +1027,8 @@ static void *multifd_send_thread(void *opaque)
>              p->pages->used = 0;
>              qemu_mutex_unlock(&p->mutex);
>  
> -            trace_multifd_send(p->id, packet_num, used, flags);
> +            trace_multifd_send(p->id, packet_num, used, flags,
> +                               p->next_packet_size);
>  
>              ret = qio_channel_write_all(p->c, (void *)p->packet,
>                                          p->packet_len, &local_err);
> @@ -1253,7 +1263,8 @@ static void *multifd_recv_thread(void *opaque)
>  
>          used = p->pages->used;
>          flags = p->flags;
> -        trace_multifd_recv(p->id, p->packet_num, used, flags);
> +        trace_multifd_recv(p->id, p->packet_num, used, flags,
> +                           p->next_packet_size);
>          p->num_packets++;
>          p->num_pages += used;
>          qemu_mutex_unlock(&p->mutex);
> diff --git a/migration/trace-events b/migration/trace-events
> index bd2d0cd25a..a11e66e1d9 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -77,13 +77,13 @@ get_queued_page_not_dirty(const char *block_name, 
> uint64_t tmp_offset, unsigned
>  migration_bitmap_sync_start(void) ""
>  migration_bitmap_sync_end(uint64_t dirty_pages) "dirty_pages %" PRIu64
>  migration_throttle(void) ""
> -multifd_recv(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags) 
> "channel %d packet number %" PRIu64 " pages %d flags 0x%x"
> +multifd_recv(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags, 
> uint32_t next_packet_size) "channel %d packet number %" PRIu64 " pages %d 
> flags 0x%x next packet size %d"
>  multifd_recv_sync_main(long packet_num) "packet num %ld"
>  multifd_recv_sync_main_signal(uint8_t id) "channel %d"
>  multifd_recv_sync_main_wait(uint8_t id) "channel %d"
>  multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t pages) 
> "channel %d packets %" PRIu64 " pages %" PRIu64
>  multifd_recv_thread_start(uint8_t id) "%d"
> -multifd_send(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags) 
> "channel %d packet_num %" PRIu64 " pages %d flags 0x%x"
> +multifd_send(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags, 
> uint32_t next_packet_size) "channel %d packet_num %" PRIu64 " pages %d flags 
> 0x%x next packet size %d"
>  multifd_send_sync_main(long packet_num) "packet num %ld"
>  multifd_send_sync_main_signal(uint8_t id) "channel %d"
>  multifd_send_sync_main_wait(uint8_t id) "channel %d"
> -- 
> 2.20.1
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK