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Blame SOURCES/kvm-migration-move-calling-save_zero_page-to-the-common-.patch

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From ea016aa3636ce101148bb6246d86474fc1cdcbf8 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Wed, 1 Aug 2018 13:55:12 +0100
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Subject: [PATCH 08/21] migration: move calling save_zero_page to the common
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 place
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20180801135522.11658-9-dgilbert@redhat.com>
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Patchwork-id: 81582
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O-Subject: [qemu-kvm RHEL8/virt212 PATCH 08/18] migration: move calling save_zero_page to the common place
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Bugzilla: 1594384
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RH-Acked-by: Peter Xu <peterx@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Juan Quintela <quintela@redhat.com>
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From: Xiao Guangrong <xiaoguangrong@tencent.com>
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save_zero_page() is always our first approach to try, move it to
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the common place before calling ram_save_compressed_page
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and ram_save_page
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Reviewed-by: Peter Xu <peterx@redhat.com>
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Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
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Message-Id: <20180330075128.26919-9-xiaoguangrong@tencent.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit d7400a3409982a52ac451cd3ca9caee9db670ca7)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 migration/ram.c | 105 +++++++++++++++++++++++++++++++-------------------------
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 1 file changed, 59 insertions(+), 46 deletions(-)
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diff --git a/migration/ram.c b/migration/ram.c
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index 9d6c41c..6e8a7e2 100644
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--- a/migration/ram.c
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+++ b/migration/ram.c
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@@ -1039,15 +1039,8 @@ static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)
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     trace_ram_save_page(block->idstr, (uint64_t)offset, p);
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     XBZRLE_cache_lock();
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-    pages = save_zero_page(rs, block, offset);
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-    if (pages > 0) {
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-        /* Must let xbzrle know, otherwise a previous (now 0'd) cached
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-         * page would be stale
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-         */
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-        xbzrle_cache_zero_page(rs, current_addr);
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-        ram_release_pages(block->idstr, offset, pages);
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-    } else if (!rs->ram_bulk_stage &&
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-               !migration_in_postcopy() && migrate_use_xbzrle()) {
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+    if (!rs->ram_bulk_stage && !migration_in_postcopy() &&
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+        migrate_use_xbzrle()) {
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         pages = save_xbzrle_page(rs, &p, current_addr, block,
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                                  offset, last_stage);
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         if (!last_stage) {
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@@ -1195,40 +1188,23 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
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     p = block->host + offset;
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-    /* When starting the process of a new block, the first page of
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-     * the block should be sent out before other pages in the same
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-     * block, and all the pages in last block should have been sent
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-     * out, keeping this order is important, because the 'cont' flag
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-     * is used to avoid resending the block name.
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-     */
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     if (block != rs->last_sent_block) {
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-        flush_compressed_data(rs);
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-        pages = save_zero_page(rs, block, offset);
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-        if (pages > 0) {
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-            ram_release_pages(block->idstr, offset, pages);
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-        } else {
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-            /*
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-             * Make sure the first page is sent out before other pages.
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-             *
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-             * we post it as normal page as compression will take much
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-             * CPU resource.
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-             */
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-            ram_counters.transferred += save_page_header(rs, rs->f, block,
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-                                            offset | RAM_SAVE_FLAG_PAGE);
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-            qemu_put_buffer_async(rs->f, p, TARGET_PAGE_SIZE,
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-                                  migrate_release_ram() &
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-                                  migration_in_postcopy());
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-            ram_counters.transferred += TARGET_PAGE_SIZE;
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-            ram_counters.normal++;
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-            pages = 1;
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-        }
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+        /*
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+         * Make sure the first page is sent out before other pages.
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+         *
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+         * we post it as normal page as compression will take much
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+         * CPU resource.
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+         */
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+        ram_counters.transferred += save_page_header(rs, rs->f, block,
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+                                        offset | RAM_SAVE_FLAG_PAGE);
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+        qemu_put_buffer_async(rs->f, p, TARGET_PAGE_SIZE,
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+                              migrate_release_ram() &
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+                              migration_in_postcopy());
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+        ram_counters.transferred += TARGET_PAGE_SIZE;
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+        ram_counters.normal++;
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+        pages = 1;
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     } else {
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-        pages = save_zero_page(rs, block, offset);
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-        if (pages == -1) {
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-            pages = compress_page_with_multi_thread(rs, block, offset);
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-        } else {
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-            ram_release_pages(block->idstr, offset, pages);
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-        }
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+        pages = compress_page_with_multi_thread(rs, block, offset);
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     }
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     return pages;
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@@ -1470,6 +1446,24 @@ err:
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     return -1;
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 }
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+static bool save_page_use_compression(RAMState *rs)
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+{
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+    if (!migrate_use_compression()) {
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+        return false;
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+    }
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+
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+    /*
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+     * If xbzrle is on, stop using the data compression after first
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+     * round of migration even if compression is enabled. In theory,
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+     * xbzrle can do better than compression.
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+     */
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+    if (rs->ram_bulk_stage || !migrate_use_xbzrle()) {
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+        return true;
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+    }
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+
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+    return false;
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+}
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+
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 /**
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  * ram_save_target_page: save one target page
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  *
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@@ -1491,12 +1485,31 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
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     }
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     /*
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-     * If xbzrle is on, stop using the data compression after first
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-     * round of migration even if compression is enabled. In theory,
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-     * xbzrle can do better than compression.
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+     * When starting the process of a new block, the first page of
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+     * the block should be sent out before other pages in the same
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+     * block, and all the pages in last block should have been sent
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+     * out, keeping this order is important, because the 'cont' flag
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+     * is used to avoid resending the block name.
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      */
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-    if (migrate_use_compression() &&
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-        (rs->ram_bulk_stage || !migrate_use_xbzrle())) {
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+    if (block != rs->last_sent_block && save_page_use_compression(rs)) {
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+            flush_compressed_data(rs);
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+    }
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+
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+    res = save_zero_page(rs, block, offset);
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+    if (res > 0) {
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+        /* Must let xbzrle know, otherwise a previous (now 0'd) cached
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+         * page would be stale
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+         */
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+        if (!save_page_use_compression(rs)) {
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+            XBZRLE_cache_lock();
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+            xbzrle_cache_zero_page(rs, block->offset + offset);
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+            XBZRLE_cache_unlock();
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+        }
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+        ram_release_pages(block->idstr, offset, res);
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+        return res;
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+    }
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+
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+    if (save_page_use_compression(rs)) {
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         return ram_save_compressed_page(rs, pss, last_stage);
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     }
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-- 
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1.8.3.1
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