Re: [Qemu-devel] [RFC PATCH V5 3/4] colo-compare: introduce packet comparison thread

[Jason Wang <jasowang@redhat.com>]

On 2016年06月23日 19:34, Zhang Chen wrote:
> if packets are same, we send primary packet and drop secondary
> packet, otherwise notify COLO do checkpoint.

More verbose please, e.g how to handle each case of exception (or maybe 
comment in the code).

>
> Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>   net/colo-base.c    |   1 +
>   net/colo-base.h    |   3 +
>   net/colo-compare.c | 214 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>   trace-events       |   2 +
>   4 files changed, 220 insertions(+)
>
> diff --git a/net/colo-base.c b/net/colo-base.c
> index 7e263e8..9673661 100644
> --- a/net/colo-base.c
> +++ b/net/colo-base.c
> @@ -146,6 +146,7 @@ Packet *packet_new(const void *data, int size)
>   
>       pkt->data = g_memdup(data, size);
>       pkt->size = size;
> +    pkt->creation_ms = qemu_clock_get_ms(QEMU_CLOCK_HOST);
>   
>       return pkt;
>   }
> diff --git a/net/colo-base.h b/net/colo-base.h
> index 01c1a5d..8bb1043 100644
> --- a/net/colo-base.h
> +++ b/net/colo-base.h
> @@ -18,6 +18,7 @@
>   #include "slirp/slirp.h"
>   #include "qemu/jhash.h"
>   #include "qemu/rcu.h"
> +#include "qemu/timer.h"
>   
>   #define HASHTABLE_MAX_SIZE 16384
>   
> @@ -47,6 +48,8 @@ typedef struct Packet {
>       };
>       uint8_t *transport_layer;
>       int size;
> +    /* Time of packet creation, in wall clock ms */
> +    int64_t creation_ms;
>   } Packet;
>   
>   typedef struct ConnectionKey {
> diff --git a/net/colo-compare.c b/net/colo-compare.c
> index 4231fe7..928d729 100644
> --- a/net/colo-compare.c
> +++ b/net/colo-compare.c
> @@ -35,6 +35,8 @@
>       OBJECT_CHECK(CompareState, (obj), TYPE_COLO_COMPARE)
>   
>   #define COMPARE_READ_LEN_MAX NET_BUFSIZE
> +/* TODO: Should be configurable */
> +#define REGULAR_CHECK_MS 400

"REGULAR" seems to generic, need a better name.

>   
>   static QTAILQ_HEAD(, CompareState) net_compares =
>          QTAILQ_HEAD_INITIALIZER(net_compares);
> @@ -86,6 +88,11 @@ typedef struct CompareState {
>       GQueue unprocessed_connections;
>       /* proxy current hash size */
>       uint32_t hashtable_size;
> +    /* compare thread, a thread for each NIC */
> +    QemuThread thread;
> +    int thread_status;
> +    /* Timer used on the primary to find packets that are never matched */
> +    QEMUTimer *timer;
>   } CompareState;
>   
>   typedef struct CompareClass {
> @@ -97,6 +104,15 @@ enum {
>       SECONDARY_IN,
>   };
>   
> +enum {
> +    /* compare thread isn't started */
> +    COMPARE_THREAD_NONE,
> +    /* compare thread is running */
> +    COMPARE_THREAD_RUNNING,
> +    /* compare thread exit */
> +    COMPARE_THREAD_EXIT,
> +};
> +
>   static int compare_chr_send(CharDriverState *out,
>                               const uint8_t *buf,
>                               uint32_t size);
> @@ -143,6 +159,98 @@ static int packet_enqueue(CompareState *s, int mode)
>       return 0;
>   }
>   
> +/*
> + * The IP packets sent by primary and secondary
> + * will be compared in here
> + * TODO support ip fragment, Out-Of-Order
> + * return:    0  means packet same
> + *            > 0 || < 0 means packet different
> + */
> +static int colo_packet_compare(Packet *ppkt, Packet *spkt)
> +{
> +    trace_colo_compare_ip_info(ppkt->size, inet_ntoa(ppkt->ip->ip_src),
> +                               inet_ntoa(ppkt->ip->ip_dst), spkt->size,
> +                               inet_ntoa(spkt->ip->ip_src),
> +                               inet_ntoa(spkt->ip->ip_dst));
> +
> +    if (ppkt->size == spkt->size) {
> +        return memcmp(ppkt->data, spkt->data, spkt->size);
> +    } else {
> +        return -1;
> +    }
> +}
> +
> +static int colo_packet_compare_all(Packet *spkt, Packet *ppkt)
> +{
> +    trace_colo_compare_main("compare all");
> +    return colo_packet_compare(ppkt, spkt);
> +}
> +
> +static void colo_old_packet_check(void *opaque_packet, void *opaque_found)
> +{
> +    int64_t now;
> +    bool *found_old = (bool *)opaque_found;
> +    Packet *ppkt = (Packet *)opaque_packet;
> +
> +    if (*found_old) {
> +        /* Someone found an old packet earlier in the queue */
> +        return;
> +    }
> +
> +    now = qemu_clock_get_ms(QEMU_CLOCK_HOST);
> +    if ((ppkt->creation_ms < now) &&

Any case that ppkt->creation_ms >= now?

> +        ((now - ppkt->creation_ms) > REGULAR_CHECK_MS)) {
> +        trace_colo_old_packet_check_found(ppkt->creation_ms);
> +        *found_old = true;
> +    }
> +}
> +
> +/*
> + * called from the compare thread on the primary
> + * for compare connection
> + */
> +static void colo_compare_connection(void *opaque, void *user_data)
> +{
> +    CompareState *s = user_data;
> +    Connection *conn = opaque;
> +    Packet *pkt = NULL;
> +    GList *result = NULL;
> +    bool found_old;
> +    int ret;
> +
> +    while (!g_queue_is_empty(&conn->primary_list) &&
> +           !g_queue_is_empty(&conn->secondary_list)) {
> +        pkt = g_queue_pop_tail(&conn->primary_list);
> +        result = g_queue_find_custom(&conn->secondary_list,
> +                              pkt, (GCompareFunc)colo_packet_compare_all);
> +
> +        if (result) {
> +            ret = compare_chr_send(s->chr_out, pkt->data, pkt->size);
> +            if (ret < 0) {
> +                error_report("colo_send_primary_packet failed");
> +            }
> +            trace_colo_compare_main("packet same and release packet");
> +            g_queue_remove(&conn->secondary_list, result->data);
> +        } else {

A question I forget the answer, so may ask again. What if secondary 
packet comes late?

> +            trace_colo_compare_main("packet different");
> +            g_queue_push_tail(&conn->primary_list, pkt);
> +            /* TODO: colo_notify_checkpoint();*/
> +            break;
> +        }
> +    }
> +
> +    /*
> +     * Look for old packets that the secondary hasn't matched,
> +     * if we have some then we have to checkpoint to wake
> +     * the secondary up.
> +     */
> +    found_old = false;
> +    g_queue_foreach(&conn->primary_list, colo_old_packet_check, &found_old);
> +    if (found_old) {
> +        /* TODO: colo_notify_checkpoint();*/

Shouldn't we need to remove all "old" packets here?

> +    }
> +}
> +
>   static int compare_chr_send(CharDriverState *out,
>                               const uint8_t *buf,
>                               uint32_t size)
> @@ -170,6 +278,69 @@ err:
>       return ret < 0 ? ret : -EIO;
>   }
>   
> +static int compare_chr_can_read(void *opaque)
> +{
> +    return COMPARE_READ_LEN_MAX;
> +}
> +
> +/*
> + * called from the main thread on the primary for packets
> + * arriving over the socket from the primary.
> + */
> +static void compare_pri_chr_in(void *opaque, const uint8_t *buf, int size)
> +{
> +    CompareState *s = COLO_COMPARE(opaque);
> +    int ret;
> +
> +    ret = net_fill_rstate(&s->pri_rs, buf, size);
> +    if (ret == -1) {
> +        qemu_chr_add_handlers(s->chr_pri_in, NULL, NULL, NULL, NULL);
> +        error_report("colo-compare primary_in error");
> +    }
> +}
> +
> +/*
> + * called from the main thread on the primary for packets
> + * arriving over the socket from the secondary.
> + */
> +static void compare_sec_chr_in(void *opaque, const uint8_t *buf, int size)
> +{
> +    CompareState *s = COLO_COMPARE(opaque);
> +    int ret;
> +
> +    ret = net_fill_rstate(&s->sec_rs, buf, size);
> +    if (ret == -1) {
> +        qemu_chr_add_handlers(s->chr_sec_in, NULL, NULL, NULL, NULL);
> +        error_report("colo-compare secondary_in error");
> +    }
> +}
> +
> +static void *colo_compare_thread(void *opaque)
> +{
> +    GMainContext *worker_context;
> +    GMainLoop *compare_loop;
> +    CompareState *s = opaque;
> +
> +    worker_context = g_main_context_new();
> +    g_assert(g_main_context_get_thread_default() == NULL);
> +    g_main_context_push_thread_default(worker_context);
> +    g_assert(g_main_context_get_thread_default() == worker_context);
> +
> +    qemu_chr_add_handlers(s->chr_pri_in, compare_chr_can_read,
> +                          compare_pri_chr_in, NULL, s);
> +    qemu_chr_add_handlers(s->chr_sec_in, compare_chr_can_read,
> +                          compare_sec_chr_in, NULL, s);
> +
> +    compare_loop = g_main_loop_new(worker_context, FALSE);
> +
> +    g_main_loop_run(compare_loop);
> +
> +    g_main_loop_unref(compare_loop);
> +    g_main_context_pop_thread_default(worker_context);
> +    g_main_context_unref(worker_context);
> +    return NULL;
> +}
> +
>   static char *compare_get_pri_indev(Object *obj, Error **errp)
>   {
>       CompareState *s = COLO_COMPARE(obj);
> @@ -222,6 +393,9 @@ static void compare_pri_rs_finalize(SocketReadState *pri_rs)
>       if (packet_enqueue(s, PRIMARY_IN)) {
>           trace_colo_compare_main("primary: unsupported packet in");
>           compare_chr_send(s->chr_out, pri_rs->buf, pri_rs->packet_len);
> +    } else {
> +        /* compare connection */
> +        g_queue_foreach(&s->conn_list, colo_compare_connection, s);
>       }
>   }
>   
> @@ -231,16 +405,35 @@ static void compare_sec_rs_finalize(SocketReadState *sec_rs)
>   
>       if (packet_enqueue(s, SECONDARY_IN)) {
>           trace_colo_compare_main("secondary: unsupported packet in");
> +    } else {
> +        /* compare connection */
> +        g_queue_foreach(&s->conn_list, colo_compare_connection, s);
>       }
>   }
>   
>   /*
> + * Prod the compare thread regularly so it can watch for any packets
> + * that the secondary hasn't produced equivalents of.
> + */
> +static void colo_compare_regular(void *opaque)
> +{
> +    CompareState *s = opaque;
> +
> +    timer_mod(s->timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
> +                        REGULAR_CHECK_MS);
> +    /* compare connection */
> +    g_queue_foreach(&s->conn_list, colo_compare_connection, s);
> +}

We need make sure this function was called from colo thread, but it 
looks not?

> +
> +/*
>    * called from the main thread on the primary
>    * to setup colo-compare.
>    */
>   static void colo_compare_complete(UserCreatable *uc, Error **errp)
>   {
>       CompareState *s = COLO_COMPARE(uc);
> +    char thread_name[64];
> +    static int compare_id;
>   
>       if (!s->pri_indev || !s->sec_indev || !s->outdev) {
>           error_setg(errp, "colo compare needs 'primary_in' ,"
> @@ -293,6 +486,19 @@ static void colo_compare_complete(UserCreatable *uc, Error **errp)
>                                                         g_free,
>                                                         connection_destroy);
>   
> +    s->thread_status = COMPARE_THREAD_RUNNING;
> +    sprintf(thread_name, "compare %d", compare_id);
> +    qemu_thread_create(&s->thread, thread_name,
> +                       colo_compare_thread, s,
> +                       QEMU_THREAD_JOINABLE);
> +    compare_id++;
> +
> +    /* A regular timer to kick any packets that the secondary doesn't match */
> +    s->timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, /* Only when guest runs */
> +                            colo_compare_regular, s);
> +    timer_mod(s->timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
> +                        REGULAR_CHECK_MS);
> +
>       return;
>   }
>   
> @@ -338,6 +544,14 @@ static void colo_compare_finalize(Object *obj)
>       qemu_mutex_destroy(&s->conn_list_lock);
>       g_queue_free(&s->conn_list);
>   
> +    if (s->thread.thread) {
> +        s->thread_status = COMPARE_THREAD_EXIT;

Looks like there's not any code that depends on the status, so why need 
to this>

> +        /* compare connection */
> +        g_queue_foreach(&s->conn_list, colo_compare_connection, s);
> +        qemu_thread_join(&s->thread);
> +    }
> +    timer_del(s->timer);
> +
>       g_free(s->pri_indev);
>       g_free(s->sec_indev);
>       g_free(s->outdev);
> diff --git a/trace-events b/trace-events
> index 703de1a..1537e91 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -1919,3 +1919,5 @@ aspeed_vic_write(uint64_t offset, unsigned size, uint32_t data) "To 0x%" PRIx64
>   
>   # net/colo-compare.c
>   colo_compare_main(const char *chr) ": %s"
> +colo_compare_ip_info(int psize, const char *sta, const char *stb, int ssize, const char *stc, const char *std) "ppkt size = %d, ip_src = %s, ip_dst = %s, spkt size = %d, ip_src = %s, ip_dst = %s"
> +colo_old_packet_check_found(int64_t old_time) "%" PRId64