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


From: Jason Wang
Subject: Re: [Qemu-devel] [RFC PATCH V5 3/4] colo-compare: introduce packet comparison thread
Date: Fri, 8 Jul 2016 12:23:50 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0



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 <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Wen Congyang <address@hidden>
---
  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




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