diff mbox

[6/8] migration: move calling save_zero_page to the common place

Message ID 20180313075739.11194-7-xiaoguangrong@tencent.com (mailing list archive)
State New, archived
Headers show

Commit Message

Xiao Guangrong March 13, 2018, 7:57 a.m. UTC
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

Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
---
 migration/ram.c | 106 ++++++++++++++++++++++++++++++++------------------------
 1 file changed, 60 insertions(+), 46 deletions(-)

Comments

Dr. David Alan Gilbert March 15, 2018, 12:27 p.m. UTC | #1
* guangrong.xiao@gmail.com (guangrong.xiao@gmail.com) wrote:
> 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
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
> ---
>  migration/ram.c | 106 ++++++++++++++++++++++++++++++++------------------------
>  1 file changed, 60 insertions(+), 46 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 839665d866..9627ce18e9 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1021,15 +1021,8 @@ 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) {
> @@ -1172,40 +1165,23 @@ 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;
> @@ -1447,6 +1423,25 @@ 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
>   *
> @@ -1472,12 +1467,31 @@ 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)) {

This test is quite interesting; I think the
reason it's different in the compression case is that since we don't put
any none-0 data in the xbzrle cache, we don't need to knock any old
none-0 pages out of the cache.

> +                XBZRLE_cache_lock();
> +                xbzrle_cache_zero_page(rs, block->offset + offset);
> +                XBZRLE_cache_unlock();
> +            }
> +            ram_release_pages(block->idstr, offset, res);
> +            goto page_saved;
> +        }
> +
> +        if (save_page_use_compression(rs)) {
>              res = ram_save_compressed_page(rs, pss, last_stage);
>          } else {
>              res = ram_save_page(rs, pss, last_stage);


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

> -- 
> 2.14.3
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Peter Xu March 27, 2018, 12:49 p.m. UTC | #2
On Tue, Mar 13, 2018 at 03:57:37PM +0800, guangrong.xiao@gmail.com wrote:
> 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
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
> ---
>  migration/ram.c | 106 ++++++++++++++++++++++++++++++++------------------------
>  1 file changed, 60 insertions(+), 46 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 839665d866..9627ce18e9 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1021,15 +1021,8 @@ 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()) {

Nit: indent problem?

[...]

> +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;
> +

Nit: remove this line?

Otherwise I'd say I like this patch... :)

Better with the nit fixed:

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

Thanks,
diff mbox

Patch

diff --git a/migration/ram.c b/migration/ram.c
index 839665d866..9627ce18e9 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1021,15 +1021,8 @@  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) {
@@ -1172,40 +1165,23 @@  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;
@@ -1447,6 +1423,25 @@  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
  *
@@ -1472,12 +1467,31 @@  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);
+            goto page_saved;
+        }
+
+        if (save_page_use_compression(rs)) {
             res = ram_save_compressed_page(rs, pss, last_stage);
         } else {
             res = ram_save_page(rs, pss, last_stage);