multifd: Use normal pages array on the send side

We are only sending normal pages through multifd channels.
Later on this series, we are going to also send zero pages.
We are going to detect if a page is zero or non zero in the multifd
channel thread, not on the main thread.

So we receive an array of pages page->offset[N]

And we will end with:

p->normal[N - zero_pages]
p->zero[zero_pages].

In this patch, we just copy all the pages in offset to normal.

for (i = 0; i < pages->num; i++) {
    p->narmal[p->normal_num] = pages->offset[i];
    p->normal_num++:
}

Later in the series this becomes:

for (i = 0; i < pages->num; i++) {
    if (buffer_is_zero(page->offset[i])) {
        p->zerol[p->zero_num] = pages->offset[i];
        p->zero_num++:
    } else {
        p->narmal[p->normal_num] = pages->offset[i];
        p->normal_num++:
    }
}

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

---

Improving comment (dave)
Renaming num_normal_pages to total_normal_pages (peter)

5 files changed, 33 insertions, 21 deletions

diff --git a/migration/multifd-zlib.c b/migration/multifd-zlib.c
index ba90f1aaf4..7f4fbef2c9 100644
--- a/migration/multifd-zlib.c
+++ b/migration/multifd-zlib.c
@@ -106,16 +106,16 @@ static int zlib_send_prepare(MultiFDSendParams *p, Error **errp)
     int ret;
     uint32_t i;
 
-    for (i = 0; i < p->pages->num; i++) {
+    for (i = 0; i < p->normal_num; i++) {
         uint32_t available = z->zbuff_len - out_size;
         int flush = Z_NO_FLUSH;
 
-        if (i == p->pages->num - 1) {
+        if (i == p->normal_num - 1) {
             flush = Z_SYNC_FLUSH;
         }
 
         zs->avail_in = page_size;
-        zs->next_in = p->pages->block->host + p->pages->offset[i];
+        zs->next_in = p->pages->block->host + p->normal[i];
 
         zs->avail_out = available;
         zs->next_out = z->zbuff + out_size;
diff --git a/migration/multifd-zstd.c b/migration/multifd-zstd.c
index 757434d1ee..907d07805c 100644
--- a/migration/multifd-zstd.c
+++ b/migration/multifd-zstd.c
@@ -121,13 +121,13 @@ static int zstd_send_prepare(MultiFDSendParams *p, Error **errp)
     z->out.size = z->zbuff_len;
     z->out.pos = 0;
 
-    for (i = 0; i < p->pages->num; i++) {
+    for (i = 0; i < p->normal_num; i++) {
         ZSTD_EndDirective flush = ZSTD_e_continue;
 
-        if (i == p->pages->num - 1) {
+        if (i == p->normal_num - 1) {
             flush = ZSTD_e_flush;
         }
-        z->in.src = p->pages->block->host + p->pages->offset[i];
+        z->in.src = p->pages->block->host + p->normal[i];
         z->in.size = page_size;
         z->in.pos = 0;
 
diff --git a/migration/multifd.c b/migration/multifd.c
index e5b1fa5015..7b804928a2 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -89,13 +89,13 @@ static int nocomp_send_prepare(MultiFDSendParams *p, Error **errp)
     MultiFDPages_t *pages = p->pages;
     size_t page_size = qemu_target_page_size();
 
-    for (int i = 0; i < p->pages->num; i++) {
-        p->iov[p->iovs_num].iov_base = pages->block->host + pages->offset[i];
+    for (int i = 0; i < p->normal_num; i++) {
+        p->iov[p->iovs_num].iov_base = pages->block->host + p->normal[i];
         p->iov[p->iovs_num].iov_len = page_size;
         p->iovs_num++;
     }
 
-    p->next_packet_size = p->pages->num * page_size;
+    p->next_packet_size = p->normal_num * page_size;
     p->flags |= MULTIFD_FLAG_NOCOMP;
     return 0;
 }
@@ -262,7 +262,7 @@ 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->num);
+    packet->pages_used = cpu_to_be32(p->normal_num);
     packet->next_packet_size = cpu_to_be32(p->next_packet_size);
     packet->packet_num = cpu_to_be64(p->packet_num);
 
@@ -270,9 +270,9 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
         strncpy(packet->ramblock, p->pages->block->idstr, 256);
     }
 
-    for (i = 0; i < p->pages->num; i++) {
+    for (i = 0; i < p->normal_num; i++) {
         /* there are architectures where ram_addr_t is 32 bit */
-        uint64_t temp = p->pages->offset[i];
+        uint64_t temp = p->normal[i];
 
         packet->offset[i] = cpu_to_be64(temp);
     }
@@ -559,6 +559,8 @@ void multifd_save_cleanup(void)
         p->packet = NULL;
         g_free(p->iov);
         p->iov = NULL;
+        g_free(p->normal);
+        p->normal = NULL;
         multifd_send_state->ops->send_cleanup(p, &local_err);
         if (local_err) {
             migrate_set_error(migrate_get_current(), local_err);
@@ -643,12 +645,17 @@ static void *multifd_send_thread(void *opaque)
         qemu_mutex_lock(&p->mutex);
 
         if (p->pending_job) {
-            uint32_t used = p->pages->num;
             uint64_t packet_num = p->packet_num;
             uint32_t flags = p->flags;
             p->iovs_num = 1;
+            p->normal_num = 0;
+
+            for (int i = 0; i < p->pages->num; i++) {
+                p->normal[p->normal_num] = p->pages->offset[i];
+                p->normal_num++;
+            }
 
-            if (used) {
+            if (p->normal_num) {
                 ret = multifd_send_state->ops->send_prepare(p, &local_err);
                 if (ret != 0) {
                     qemu_mutex_unlock(&p->mutex);
@@ -658,12 +665,12 @@ static void *multifd_send_thread(void *opaque)
             multifd_send_fill_packet(p);
             p->flags = 0;
             p->num_packets++;
-            p->num_pages += used;
+            p->total_normal_pages += p->normal_num;
             p->pages->num = 0;
             p->pages->block = NULL;
             qemu_mutex_unlock(&p->mutex);
 
-            trace_multifd_send(p->id, packet_num, used, flags,
+            trace_multifd_send(p->id, packet_num, p->normal_num, flags,
                                p->next_packet_size);
 
             p->iov[0].iov_len = p->packet_len;
@@ -713,7 +720,7 @@ out:
     qemu_mutex_unlock(&p->mutex);
 
     rcu_unregister_thread();
-    trace_multifd_send_thread_end(p->id, p->num_packets, p->num_pages);
+    trace_multifd_send_thread_end(p->id, p->num_packets, p->total_normal_pages);
 
     return NULL;
 }
@@ -913,6 +920,7 @@ int multifd_save_setup(Error **errp)
         p->tls_hostname = g_strdup(s->hostname);
         /* We need one extra place for the packet header */
         p->iov = g_new0(struct iovec, page_count + 1);
+        p->normal = g_new0(ram_addr_t, page_count);
         socket_send_channel_create(multifd_new_send_channel_async, p);
     }
 
diff --git a/migration/multifd.h b/migration/multifd.h
index 7496f951a7..7823199dbe 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -104,14 +104,18 @@ typedef struct {
     /* thread local variables */
     /* packets sent through this channel */
     uint64_t num_packets;
-    /* pages sent through this channel */
-    uint64_t num_pages;
+    /* non zero pages sent through this channel */
+    uint64_t total_normal_pages;
     /* syncs main thread and channels */
     QemuSemaphore sem_sync;
     /* buffers to send */
     struct iovec *iov;
     /* number of iovs used */
     uint32_t iovs_num;
+    /* Pages that are not zero */
+    ram_addr_t *normal;
+    /* num of non zero pages */
+    uint32_t normal_num;
     /* used for compression methods */
     void *data;
 }  MultiFDSendParams;
diff --git a/migration/trace-events b/migration/trace-events
index 5172cb3b3d..171a83a55d 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -124,13 +124,13 @@ multifd_recv_sync_main_wait(uint8_t id) "channel %u"
 multifd_recv_terminate_threads(bool error) "error %d"
 multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %u packets %" PRIu64 " pages %" PRIu64
 multifd_recv_thread_start(uint8_t id) "%u"
-multifd_send(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " pages %u flags 0x%x next packet size %u"
+multifd_send(uint8_t id, uint64_t packet_num, uint32_t normal, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " normal pages %u flags 0x%x next packet size %u"
 multifd_send_error(uint8_t id) "channel %u"
 multifd_send_sync_main(long packet_num) "packet num %ld"
 multifd_send_sync_main_signal(uint8_t id) "channel %u"
 multifd_send_sync_main_wait(uint8_t id) "channel %u"
 multifd_send_terminate_threads(bool error) "error %d"
-multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %u packets %" PRIu64 " pages %"  PRIu64
+multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages) "channel %u packets %" PRIu64 " normal pages %"  PRIu64
 multifd_send_thread_start(uint8_t id) "%u"
 multifd_tls_outgoing_handshake_start(void *ioc, void *tioc, const char *hostname) "ioc=%p tioc=%p hostname=%s"
 multifd_tls_outgoing_handshake_error(void *ioc, const char *err) "ioc=%p err=%s"