[PATCH v2 2/7] migration/multifd: Support for zero pages transmission in multifd format.

[Hao Xiang]

This change adds zero page counters and updates multifd send/receive
tracing format to track the newly added counters.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
---
 migration/multifd.c    | 43 ++++++++++++++++++++++++++++++++++--------
 migration/multifd.h    | 21 ++++++++++++++++++++-
 migration/ram.c        |  1 -
 migration/trace-events |  8 ++++----
 4 files changed, 59 insertions(+), 14 deletions(-)

diff --git a/migration/multifd.c b/migration/multifd.c
index adfe8c9a0a..a33dba40d9 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -236,6 +236,8 @@ static void multifd_pages_reset(MultiFDPages_t *pages)
      * overwritten later when reused.
      */
     pages->num = 0;
+    pages->normal_num = 0;
+    pages->zero_num = 0;
     pages->block = NULL;
 }
 
@@ -309,6 +311,8 @@ static MultiFDPages_t *multifd_pages_init(uint32_t n)
 
     pages->allocated = n;
     pages->offset = g_new0(ram_addr_t, n);
+    pages->normal = g_new0(ram_addr_t, n);
+    pages->zero = g_new0(ram_addr_t, n);
 
     return pages;
 }
@@ -319,6 +323,10 @@ static void multifd_pages_clear(MultiFDPages_t *pages)
     pages->allocated = 0;
     g_free(pages->offset);
     pages->offset = NULL;
+    g_free(pages->normal);
+    pages->normal = NULL;
+    g_free(pages->zero);
+    pages->zero = NULL;
     g_free(pages);
 }
 
@@ -332,6 +340,7 @@ void multifd_send_fill_packet(MultiFDSendParams *p)
     packet->flags = cpu_to_be32(p->flags);
     packet->pages_alloc = cpu_to_be32(p->pages->allocated);
     packet->normal_pages = cpu_to_be32(pages->num);
+    packet->zero_pages = cpu_to_be32(pages->zero_num);
     packet->next_packet_size = cpu_to_be32(p->next_packet_size);
 
     packet_num = qatomic_fetch_inc(&multifd_send_state->packet_num);
@@ -350,9 +359,10 @@ void multifd_send_fill_packet(MultiFDSendParams *p)
 
     p->packets_sent++;
     p->total_normal_pages += pages->num;
+    p->total_zero_pages += pages->zero_num;
 
-    trace_multifd_send(p->id, packet_num, pages->num, p->flags,
-                       p->next_packet_size);
+    trace_multifd_send(p->id, packet_num, pages->num, pages->zero_num,
+                       p->flags, p->next_packet_size);
 }
 
 static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
@@ -393,20 +403,29 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams 
*p, Error **errp)
     p->normal_num = be32_to_cpu(packet->normal_pages);
     if (p->normal_num > packet->pages_alloc) {
         error_setg(errp, "multifd: received packet "
-                   "with %u pages and expected maximum pages are %u",
+                   "with %u normal pages and expected maximum pages are %u",
                    p->normal_num, packet->pages_alloc) ;
         return -1;
     }
 
+    p->zero_num = be32_to_cpu(packet->zero_pages);
+    if (p->zero_num > packet->pages_alloc - p->normal_num) {
+        error_setg(errp, "multifd: received packet "
+                   "with %u zero pages and expected maximum zero pages are %u",
+                   p->zero_num, packet->pages_alloc - p->normal_num) ;
+        return -1;
+    }
+
     p->next_packet_size = be32_to_cpu(packet->next_packet_size);
     p->packet_num = be64_to_cpu(packet->packet_num);
     p->packets_recved++;
     p->total_normal_pages += p->normal_num;
+    p->total_zero_pages += p->zero_num;
 
-    trace_multifd_recv(p->id, p->packet_num, p->normal_num, p->flags,
-                       p->next_packet_size);
+    trace_multifd_recv(p->id, p->packet_num, p->normal_num, p->zero_num,
+                       p->flags, p->next_packet_size);
 
-    if (p->normal_num == 0) {
+    if (p->normal_num == 0 && p->zero_num == 0) {
         return 0;
     }
 
@@ -823,6 +842,8 @@ static void *multifd_send_thread(void *opaque)
 
             stat64_add(&mig_stats.multifd_bytes,
                        p->next_packet_size + p->packet_len);
+            stat64_add(&mig_stats.normal_pages, pages->num);
+            stat64_add(&mig_stats.zero_pages, pages->zero_num);
 
             multifd_pages_reset(p->pages);
             p->next_packet_size = 0;
@@ -866,7 +887,8 @@ out:
 
     rcu_unregister_thread();
     migration_threads_remove(thread);
-    trace_multifd_send_thread_end(p->id, p->packets_sent, 
p->total_normal_pages);
+    trace_multifd_send_thread_end(p->id, p->packets_sent, 
p->total_normal_pages,
+                                  p->total_zero_pages);
 
     return NULL;
 }
@@ -1132,6 +1154,8 @@ static void 
multifd_recv_cleanup_channel(MultiFDRecvParams *p)
     p->iov = NULL;
     g_free(p->normal);
     p->normal = NULL;
+    g_free(p->zero);
+    p->zero = NULL;
     multifd_recv_state->ops->recv_cleanup(p);
 }
 
@@ -1251,7 +1275,9 @@ static void *multifd_recv_thread(void *opaque)
     }
 
     rcu_unregister_thread();
-    trace_multifd_recv_thread_end(p->id, p->packets_recved, 
p->total_normal_pages);
+    trace_multifd_recv_thread_end(p->id, p->packets_recved,
+                                  p->total_normal_pages,
+                                  p->total_zero_pages);
 
     return NULL;
 }
@@ -1290,6 +1316,7 @@ int multifd_recv_setup(Error **errp)
         p->name = g_strdup_printf("multifdrecv_%d", i);
         p->iov = g_new0(struct iovec, page_count);
         p->normal = g_new0(ram_addr_t, page_count);
+        p->zero = g_new0(ram_addr_t, page_count);
         p->page_count = page_count;
         p->page_size = qemu_target_page_size();
     }
diff --git a/migration/multifd.h b/migration/multifd.h
index 8a1cad0996..9822ff298a 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -48,7 +48,10 @@ typedef struct {
     /* size of the next packet that contains pages */
     uint32_t next_packet_size;
     uint64_t packet_num;
-    uint64_t unused[4];    /* Reserved for future use */
+    /* zero pages */
+    uint32_t zero_pages;
+    uint32_t unused32[1];    /* Reserved for future use */
+    uint64_t unused64[3];    /* Reserved for future use */
     char ramblock[256];
     uint64_t offset[];
 } __attribute__((packed)) MultiFDPacket_t;
@@ -56,10 +59,18 @@ typedef struct {
 typedef struct {
     /* number of used pages */
     uint32_t num;
+    /* number of normal pages */
+    uint32_t normal_num;
+    /* number of zero pages */
+    uint32_t zero_num;
     /* number of allocated pages */
     uint32_t allocated;
     /* offset of each page */
     ram_addr_t *offset;
+    /* offset of normal page */
+    ram_addr_t *normal;
+    /* offset of zero page */
+    ram_addr_t *zero;
     RAMBlock *block;
 } MultiFDPages_t;
 
@@ -124,6 +135,8 @@ typedef struct {
     uint64_t packets_sent;
     /* non zero pages sent through this channel */
     uint64_t total_normal_pages;
+    /* zero pages sent through this channel */
+    uint64_t total_zero_pages;
     /* buffers to send */
     struct iovec *iov;
     /* number of iovs used */
@@ -178,12 +191,18 @@ typedef struct {
     uint8_t *host;
     /* non zero pages recv through this channel */
     uint64_t total_normal_pages;
+    /* zero pages recv through this channel */
+    uint64_t total_zero_pages;
     /* buffers to recv */
     struct iovec *iov;
     /* Pages that are not zero */
     ram_addr_t *normal;
     /* num of non zero pages */
     uint32_t normal_num;
+    /* Pages that are zero */
+    ram_addr_t *zero;
+    /* num of zero pages */
+    uint32_t zero_num;
     /* used for de-compression methods */
     void *data;
 } MultiFDRecvParams;
diff --git a/migration/ram.c b/migration/ram.c
index 556725c30f..5ece9f042e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1259,7 +1259,6 @@ static int ram_save_multifd_page(RAMBlock *block, 
ram_addr_t offset)
     if (!multifd_queue_page(block, offset)) {
         return -1;
     }
-    stat64_add(&mig_stats.normal_pages, 1);
 
     return 1;
 }
diff --git a/migration/trace-events b/migration/trace-events
index 298ad2b0dd..9f1d7ae71a 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -128,21 +128,21 @@ postcopy_preempt_reset_channel(void) ""
 # multifd.c
 multifd_new_send_channel_async(uint8_t id) "channel %u"
 multifd_new_send_channel_async_error(uint8_t id, void *err) "channel=%u err=%p"
-multifd_recv(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_recv(uint8_t id, uint64_t packet_num, uint32_t normal, uint32_t zero, 
uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " 
normal pages %u zero pages %u flags 0x%x next packet size %u"
 multifd_recv_new_channel(uint8_t id) "channel %u"
 multifd_recv_sync_main(long packet_num) "packet num %ld"
 multifd_recv_sync_main_signal(uint8_t id) "channel %u"
 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_end(uint8_t id, uint64_t packets, uint64_t normal_pages, 
uint64_t zero_pages) "channel %u packets %" PRIu64 " normal pages %" PRIu64 " 
zero pages %" PRIu64
 multifd_recv_thread_start(uint8_t id) "%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(uint8_t id, uint64_t packet_num, uint32_t normal_pages, uint32_t 
zero_pages, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num 
%" PRIu64 " normal pages %u zero 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(void) ""
-multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages) 
"channel %u packets %" PRIu64 " normal pages %"  PRIu64
+multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages, 
uint64_t zero_pages) "channel %u packets %" PRIu64 " normal pages %"  PRIu64 " 
zero 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"
-- 
2.30.2