From ea016aa3636ce101148bb6246d86474fc1cdcbf8 Mon Sep 17 00:00:00 2001

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Date: Wed, 1 Aug 2018 13:55:12 +0100

Subject: [PATCH 08/21] migration: move calling save_zero_page to the common

 place

RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>

Message-id: <20180801135522.11658-9-dgilbert@redhat.com>

Patchwork-id: 81582

O-Subject: [qemu-kvm RHEL8/virt212 PATCH 08/18] migration: move calling save_zero_page to the common place

Bugzilla: 1594384

RH-Acked-by: Peter Xu <peterx@redhat.com>

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Juan Quintela <quintela@redhat.com>

From: Xiao Guangrong <xiaoguangrong@tencent.com>

save_zero_page() is always our first approach to try, move it to

the common place before calling ram_save_compressed_page

and ram_save_page

Reviewed-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>

Message-Id: <20180330075128.26919-9-xiaoguangrong@tencent.com>

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

(cherry picked from commit d7400a3409982a52ac451cd3ca9caee9db670ca7)

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 migration/ram.c | 105 +++++++++++++++++++++++++++++++-------------------------

 1 file changed, 59 insertions(+), 46 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c

index 9d6c41c..6e8a7e2 100644

--- a/migration/ram.c

+++ b/migration/ram.c

@@ -1039,15 +1039,8 @@ static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)

     trace_ram_save_page(block->idstr, (uint64_t)offset, p);

     XBZRLE_cache_lock();

-    pages = save_zero_page(rs, block, offset);

-    if (pages > 0) {

-        /* Must let xbzrle know, otherwise a previous (now 0'd) cached

-         * page would be stale

-         */

-        xbzrle_cache_zero_page(rs, current_addr);

-        ram_release_pages(block->idstr, offset, pages);

-    } else if (!rs->ram_bulk_stage &&

-               !migration_in_postcopy() && migrate_use_xbzrle()) {

+    if (!rs->ram_bulk_stage && !migration_in_postcopy() &&

+        migrate_use_xbzrle()) {

         pages = save_xbzrle_page(rs, &p, current_addr, block,

                                  offset, last_stage);

         if (!last_stage) {

@@ -1195,40 +1188,23 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,

     p = block->host + offset;

-    /* When starting the process of a new block, the first page of

-     * the block should be sent out before other pages in the same

-     * block, and all the pages in last block should have been sent

-     * out, keeping this order is important, because the 'cont' flag

-     * is used to avoid resending the block name.

-     */

     if (block != rs->last_sent_block) {

-        flush_compressed_data(rs);

-        pages = save_zero_page(rs, block, offset);

-        if (pages > 0) {

-            ram_release_pages(block->idstr, offset, pages);

-        } else {

-            /*

-             * Make sure the first page is sent out before other pages.

-             *

-             * we post it as normal page as compression will take much

-             * CPU resource.

-             */

-            ram_counters.transferred += save_page_header(rs, rs->f, block,

-                                            offset | RAM_SAVE_FLAG_PAGE);

-            qemu_put_buffer_async(rs->f, p, TARGET_PAGE_SIZE,

-                                  migrate_release_ram() &

-                                  migration_in_postcopy());

-            ram_counters.transferred += TARGET_PAGE_SIZE;

-            ram_counters.normal++;

-            pages = 1;

-        }

+        /*

+         * Make sure the first page is sent out before other pages.

+         *

+         * we post it as normal page as compression will take much

+         * CPU resource.

+         */

+        ram_counters.transferred += save_page_header(rs, rs->f, block,

+                                        offset | RAM_SAVE_FLAG_PAGE);

+        qemu_put_buffer_async(rs->f, p, TARGET_PAGE_SIZE,

+                              migrate_release_ram() &

+                              migration_in_postcopy());

+        ram_counters.transferred += TARGET_PAGE_SIZE;

+        ram_counters.normal++;

+        pages = 1;

     } else {

-        pages = save_zero_page(rs, block, offset);

-        if (pages == -1) {

-            pages = compress_page_with_multi_thread(rs, block, offset);

-        } else {

-            ram_release_pages(block->idstr, offset, pages);

-        }

+        pages = compress_page_with_multi_thread(rs, block, offset);

     }

     return pages;

@@ -1470,6 +1446,24 @@ err:

     return -1;

 }

+static bool save_page_use_compression(RAMState *rs)

+{

+    if (!migrate_use_compression()) {

+        return false;

+    }

+

+    /*

+     * If xbzrle is on, stop using the data compression after first

+     * round of migration even if compression is enabled. In theory,

+     * xbzrle can do better than compression.

+     */

+    if (rs->ram_bulk_stage || !migrate_use_xbzrle()) {

+        return true;

+    }

+

+    return false;

+}

+

 /**

  * ram_save_target_page: save one target page

  *

@@ -1491,12 +1485,31 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,

     }

     /*

-     * If xbzrle is on, stop using the data compression after first

-     * round of migration even if compression is enabled. In theory,

-     * xbzrle can do better than compression.

+     * When starting the process of a new block, the first page of

+     * the block should be sent out before other pages in the same

+     * block, and all the pages in last block should have been sent

+     * out, keeping this order is important, because the 'cont' flag

+     * is used to avoid resending the block name.

      */

-    if (migrate_use_compression() &&

-        (rs->ram_bulk_stage || !migrate_use_xbzrle())) {

+    if (block != rs->last_sent_block && save_page_use_compression(rs)) {

+            flush_compressed_data(rs);

+    }

+

+    res = save_zero_page(rs, block, offset);

+    if (res > 0) {

+        /* Must let xbzrle know, otherwise a previous (now 0'd) cached

+         * page would be stale

+         */

+        if (!save_page_use_compression(rs)) {

+            XBZRLE_cache_lock();

+            xbzrle_cache_zero_page(rs, block->offset + offset);

+            XBZRLE_cache_unlock();

+        }

+        ram_release_pages(block->idstr, offset, res);

+        return res;

+    }

+

+    if (save_page_use_compression(rs)) {

         return ram_save_compressed_page(rs, pss, last_stage);

     }

-- 

1.8.3.1