Re: [PATCH v3 2/2] net/colo-compare.c: handling of the full primary or secondary queue

[Lukas Straub]

On Wed, 25 Mar 2020 17:43:54 +0800
Derek Su <address@hidden> wrote:

> The pervious handling of the full primary or queue is only dropping
> the packet. If there are lots of clients to the guest VM,
> the "drop" will lead to the lost of the networking connection
> until next checkpoint.
> 
> To address the issue, this patch drops the packet firstly.
> Then, send all queued primary packets, remove all queued secondary
> packets and do checkpoint.
> 
> Signed-off-by: Derek Su <address@hidden>
> ---
>  net/colo-compare.c | 41 ++++++++++++++++++++++++++++++-----------
>  1 file changed, 30 insertions(+), 11 deletions(-)
> 
> diff --git a/net/colo-compare.c b/net/colo-compare.c
> index cdd87b2aa8..1a52f50fbe 100644
> --- a/net/colo-compare.c
> +++ b/net/colo-compare.c
> @@ -125,6 +125,12 @@ static const char *colo_mode[] = {
>      [SECONDARY_IN] = "secondary",
>  };
>  
> +enum {
> +    QUEUE_INSERT_ERR = -1,
> +    QUEUE_INSERT_OK = 0,
> +    QUEUE_INSERT_FULL = 1,
> +};
> +
>  static int compare_chr_send(CompareState *s,
>                              const uint8_t *buf,
>                              uint32_t size,
> @@ -211,8 +217,10 @@ static int colo_insert_packet(GQueue *queue, Packet 
> *pkt, uint32_t *max_ack)
>  }
>  
>  /*
> - * Return 0 on success, if return -1 means the pkt
> - * is unsupported(arp and ipv6) and will be sent later
> + * Return QUEUE_INSERT_OK on success.
> + * If return QUEUE_INSERT_FULL means list is full, and
> + * QUEUE_INSERT_ERR means the pkt is unsupported(arp and ipv6) and
> + * will be sent later
>   */
>  static int packet_enqueue(CompareState *s, int mode, Connection **con)
>  {
> @@ -234,7 +242,7 @@ static int packet_enqueue(CompareState *s, int mode, 
> Connection **con)
>      if (parse_packet_early(pkt)) {
>          packet_destroy(pkt, NULL);
>          pkt = NULL;
> -        return -1;
> +        return QUEUE_INSERT_ERR;
>      }
>      fill_connection_key(pkt, &key);
>  
> @@ -258,11 +266,12 @@ static int packet_enqueue(CompareState *s, int mode, 
> Connection **con)
>                       "drop packet", colo_mode[mode]);
>          packet_destroy(pkt, NULL);
>          pkt = NULL;
> +        return QUEUE_INSERT_FULL;
>      }
>  
>      *con = conn;
>  
> -    return 0;
> +    return QUEUE_INSERT_OK;
>  }
>  
>  static inline bool after(uint32_t seq1, uint32_t seq2)
> @@ -995,17 +1004,22 @@ static void compare_pri_rs_finalize(SocketReadState 
> *pri_rs)
>  {
>      CompareState *s = container_of(pri_rs, CompareState, pri_rs);
>      Connection *conn = NULL;
> +    int ret;
>  
> -    if (packet_enqueue(s, PRIMARY_IN, &conn)) {
> +    ret = packet_enqueue(s, PRIMARY_IN, &conn);
> +    if (ret == QUEUE_INSERT_OK) {
> +        /* compare packet in the specified connection */
> +        colo_compare_connection(conn, s);
> +    } else if (ret == QUEUE_INSERT_FULL) {
> +        g_queue_foreach(&s->conn_list, colo_flush_packets, s);
> +        colo_compare_inconsistency_notify(s);
> +    } else {
>          trace_colo_compare_main("primary: unsupported packet in");
>          compare_chr_send(s,
>                           pri_rs->buf,
>                           pri_rs->packet_len,
>                           pri_rs->vnet_hdr_len,
>                           false);
> -    } else {
> -        /* compare packet in the specified connection */
> -        colo_compare_connection(conn, s);
>      }
>  }
>  
> @@ -1013,12 +1027,17 @@ static void compare_sec_rs_finalize(SocketReadState 
> *sec_rs)
>  {
>      CompareState *s = container_of(sec_rs, CompareState, sec_rs);
>      Connection *conn = NULL;
> +    int ret;
>  
> -    if (packet_enqueue(s, SECONDARY_IN, &conn)) {
> -        trace_colo_compare_main("secondary: unsupported packet in");
> -    } else {
> +    ret = packet_enqueue(s, SECONDARY_IN, &conn);
> +    if (ret == QUEUE_INSERT_OK) {
>          /* compare packet in the specified connection */
>          colo_compare_connection(conn, s);
> +    } else if (ret == QUEUE_INSERT_FULL) {
> +        g_queue_foreach(&s->conn_list, colo_flush_packets, s);
> +        colo_compare_inconsistency_notify(s);
> +    } else {
> +        trace_colo_compare_main("secondary: unsupported packet in");
>      }
>  }
>  

Hi,
I don't think we have to flush here because the (post-)checkpoint event will 
flush the packets for us.

Regards,
Lukas Straub

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