Blame SOURCES/kvm-multifd-Use-normal-pages-array-on-the-send-side.patch

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From 3b57c876e1eaca34fb5bd9067553de945013d4be Mon Sep 17 00:00:00 2001
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From: Juan Quintela <quintela@redhat.com>
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Date: Wed, 18 May 2022 02:52:24 -0300
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Subject: [PATCH 16/37] multifd: Use normal pages array on the send side
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Leonardo Brás <leobras@redhat.com>
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RH-MergeRequest: 191: MSG_ZEROCOPY + Multifd @ rhel8.7
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RH-Commit: [16/26] 1c48806474daf48fe93920ac361311af95c6a6f3
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RH-Bugzilla: 2072049
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RH-Acked-by: Peter Xu <peterx@redhat.com>
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RH-Acked-by: Daniel P. Berrangé <berrange@redhat.com>
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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We are only sending normal pages through multifd channels.
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Later on this series, we are going to also send zero pages.
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We are going to detect if a page is zero or non zero in the multifd
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channel thread, not on the main thread.
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So we receive an array of pages page->offset[N]
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And we will end with:
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p->normal[N - zero_pages]
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p->zero[zero_pages].
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In this patch, we just copy all the pages in offset to normal.
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for (i = 0; i < pages->num; i++) {
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    p->narmal[p->normal_num] = pages->offset[i];
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    p->normal_num++:
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}
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Later in the series this becomes:
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for (i = 0; i < pages->num; i++) {
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    if (buffer_is_zero(page->offset[i])) {
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        p->zerol[p->zero_num] = pages->offset[i];
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        p->zero_num++:
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    } else {
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        p->narmal[p->normal_num] = pages->offset[i];
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        p->normal_num++:
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    }
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}
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Signed-off-by: Juan Quintela <quintela@redhat.com>
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Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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---
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Improving comment (dave)
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Renaming num_normal_pages to total_normal_pages (peter)
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(cherry picked from commit 815956f03902980c771da64b17f7f791c1cb57b0)
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Signed-off-by: Leonardo Bras <leobras@redhat.com>
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---
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 migration/multifd-zlib.c |  6 +++---
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 migration/multifd-zstd.c |  6 +++---
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 migration/multifd.c      | 30 +++++++++++++++++++-----------
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 migration/multifd.h      |  8 ++++++--
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 migration/trace-events   |  4 ++--
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 5 files changed, 33 insertions(+), 21 deletions(-)
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diff --git a/migration/multifd-zlib.c b/migration/multifd-zlib.c
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index 8ed29b9633..8508f26adf 100644
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--- a/migration/multifd-zlib.c
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+++ b/migration/multifd-zlib.c
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@@ -108,16 +108,16 @@ static int zlib_send_prepare(MultiFDSendParams *p, Error **errp)
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     int ret;
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     uint32_t i;
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-    for (i = 0; i < p->pages->num; i++) {
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+    for (i = 0; i < p->normal_num; i++) {
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         uint32_t available = z->zbuff_len - out_size;
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         int flush = Z_NO_FLUSH;
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-        if (i == p->pages->num - 1) {
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+        if (i == p->normal_num - 1) {
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             flush = Z_SYNC_FLUSH;
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         }
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         zs->avail_in = page_size;
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-        zs->next_in = p->pages->block->host + p->pages->offset[i];
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+        zs->next_in = p->pages->block->host + p->normal[i];
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         zs->avail_out = available;
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         zs->next_out = z->zbuff + out_size;
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diff --git a/migration/multifd-zstd.c b/migration/multifd-zstd.c
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index 25e1f517b5..693af3a140 100644
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--- a/migration/multifd-zstd.c
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+++ b/migration/multifd-zstd.c
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@@ -123,13 +123,13 @@ static int zstd_send_prepare(MultiFDSendParams *p, Error **errp)
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     z->out.size = z->zbuff_len;
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     z->out.pos = 0;
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-    for (i = 0; i < p->pages->num; i++) {
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+    for (i = 0; i < p->normal_num; i++) {
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         ZSTD_EndDirective flush = ZSTD_e_continue;
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-        if (i == p->pages->num - 1) {
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+        if (i == p->normal_num - 1) {
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             flush = ZSTD_e_flush;
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         }
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-        z->in.src = p->pages->block->host + p->pages->offset[i];
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+        z->in.src = p->pages->block->host + p->normal[i];
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         z->in.size = page_size;
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         z->in.pos = 0;
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diff --git a/migration/multifd.c b/migration/multifd.c
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index d0f86542b1..3725226400 100644
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--- a/migration/multifd.c
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+++ b/migration/multifd.c
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@@ -89,13 +89,13 @@ static int nocomp_send_prepare(MultiFDSendParams *p, Error **errp)
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     MultiFDPages_t *pages = p->pages;
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     size_t page_size = qemu_target_page_size();
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-    for (int i = 0; i < p->pages->num; i++) {
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-        p->iov[p->iovs_num].iov_base = pages->block->host + pages->offset[i];
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+    for (int i = 0; i < p->normal_num; i++) {
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+        p->iov[p->iovs_num].iov_base = pages->block->host + p->normal[i];
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         p->iov[p->iovs_num].iov_len = page_size;
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         p->iovs_num++;
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     }
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-    p->next_packet_size = p->pages->num * page_size;
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+    p->next_packet_size = p->normal_num * page_size;
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     p->flags |= MULTIFD_FLAG_NOCOMP;
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     return 0;
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 }
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@@ -262,7 +262,7 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
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     packet->flags = cpu_to_be32(p->flags);
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     packet->pages_alloc = cpu_to_be32(p->pages->allocated);
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-    packet->pages_used = cpu_to_be32(p->pages->num);
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+    packet->pages_used = cpu_to_be32(p->normal_num);
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     packet->next_packet_size = cpu_to_be32(p->next_packet_size);
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     packet->packet_num = cpu_to_be64(p->packet_num);
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@@ -270,9 +270,9 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
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         strncpy(packet->ramblock, p->pages->block->idstr, 256);
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     }
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-    for (i = 0; i < p->pages->num; i++) {
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+    for (i = 0; i < p->normal_num; i++) {
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         /* there are architectures where ram_addr_t is 32 bit */
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-        uint64_t temp = p->pages->offset[i];
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+        uint64_t temp = p->normal[i];
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         packet->offset[i] = cpu_to_be64(temp);
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     }
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@@ -556,6 +556,8 @@ void multifd_save_cleanup(void)
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         p->packet = NULL;
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         g_free(p->iov);
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         p->iov = NULL;
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+        g_free(p->normal);
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+        p->normal = NULL;
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         multifd_send_state->ops->send_cleanup(p, &local_err);
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         if (local_err) {
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             migrate_set_error(migrate_get_current(), local_err);
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@@ -640,12 +642,17 @@ static void *multifd_send_thread(void *opaque)
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         qemu_mutex_lock(&p->mutex);
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         if (p->pending_job) {
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-            uint32_t used = p->pages->num;
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             uint64_t packet_num = p->packet_num;
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             uint32_t flags = p->flags;
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             p->iovs_num = 1;
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+            p->normal_num = 0;
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+
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+            for (int i = 0; i < p->pages->num; i++) {
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+                p->normal[p->normal_num] = p->pages->offset[i];
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+                p->normal_num++;
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+            }
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-            if (used) {
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+            if (p->normal_num) {
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                 ret = multifd_send_state->ops->send_prepare(p, &local_err);
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                 if (ret != 0) {
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                     qemu_mutex_unlock(&p->mutex);
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@@ -655,12 +662,12 @@ static void *multifd_send_thread(void *opaque)
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             multifd_send_fill_packet(p);
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             p->flags = 0;
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             p->num_packets++;
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-            p->num_pages += used;
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+            p->total_normal_pages += p->normal_num;
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             p->pages->num = 0;
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             p->pages->block = NULL;
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             qemu_mutex_unlock(&p->mutex);
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-            trace_multifd_send(p->id, packet_num, used, flags,
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+            trace_multifd_send(p->id, packet_num, p->normal_num, flags,
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                                p->next_packet_size);
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             p->iov[0].iov_len = p->packet_len;
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@@ -710,7 +717,7 @@ out:
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     qemu_mutex_unlock(&p->mutex);
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     rcu_unregister_thread();
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-    trace_multifd_send_thread_end(p->id, p->num_packets, p->num_pages);
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+    trace_multifd_send_thread_end(p->id, p->num_packets, p->total_normal_pages);
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     return NULL;
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 }
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@@ -910,6 +917,7 @@ int multifd_save_setup(Error **errp)
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         p->tls_hostname = g_strdup(s->hostname);
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         /* We need one extra place for the packet header */
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         p->iov = g_new0(struct iovec, page_count + 1);
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+        p->normal = g_new0(ram_addr_t, page_count);
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         socket_send_channel_create(multifd_new_send_channel_async, p);
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     }
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diff --git a/migration/multifd.h b/migration/multifd.h
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index 7496f951a7..7823199dbe 100644
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--- a/migration/multifd.h
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+++ b/migration/multifd.h
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@@ -104,14 +104,18 @@ typedef struct {
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     /* thread local variables */
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     /* packets sent through this channel */
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     uint64_t num_packets;
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-    /* pages sent through this channel */
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-    uint64_t num_pages;
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+    /* non zero pages sent through this channel */
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+    uint64_t total_normal_pages;
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     /* syncs main thread and channels */
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     QemuSemaphore sem_sync;
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     /* buffers to send */
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     struct iovec *iov;
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     /* number of iovs used */
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     uint32_t iovs_num;
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+    /* Pages that are not zero */
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+    ram_addr_t *normal;
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+    /* num of non zero pages */
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+    uint32_t normal_num;
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     /* used for compression methods */
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     void *data;
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 }  MultiFDSendParams;
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diff --git a/migration/trace-events b/migration/trace-events
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index 5172cb3b3d..171a83a55d 100644
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--- a/migration/trace-events
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+++ b/migration/trace-events
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@@ -124,13 +124,13 @@ multifd_recv_sync_main_wait(uint8_t id) "channel %u"
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 multifd_recv_terminate_threads(bool error) "error %d"
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 multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %u packets %" PRIu64 " pages %" PRIu64
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 multifd_recv_thread_start(uint8_t id) "%u"
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-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"
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+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"
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 multifd_send_error(uint8_t id) "channel %u"
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 multifd_send_sync_main(long packet_num) "packet num %ld"
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 multifd_send_sync_main_signal(uint8_t id) "channel %u"
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 multifd_send_sync_main_wait(uint8_t id) "channel %u"
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 multifd_send_terminate_threads(bool error) "error %d"
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-multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %u packets %" PRIu64 " pages %"  PRIu64
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+multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages) "channel %u packets %" PRIu64 " normal pages %"  PRIu64
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 multifd_send_thread_start(uint8_t id) "%u"
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 multifd_tls_outgoing_handshake_start(void *ioc, void *tioc, const char *hostname) "ioc=%p tioc=%p hostname=%s"
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 multifd_tls_outgoing_handshake_error(void *ioc, const char *err) "ioc=%p err=%s"
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-- 
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2.35.3
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