bzr commit into mysql-5.1-bugteam branch (svoj:3469) Bug#35077

[Sergey Vojtovich]

#At file:///home/svoj/devel/innodb-snapshots/mysql-5.1-bugteam/ based on revid:svoj@stripped

 3469 Sergey Vojtovich	2010-04-01
      Applying InnoDB snapshot, fixes BUG#35077.
      
      Detailed revision comments:
      
      r6525 | marko | 2010-01-28 16:23:15 +0200 (Thu, 28 Jan 2010) | 11 lines
      branches/zip: buf_LRU_invalidate_tablespace(): Do not unnecessarily
      acquire the block_mutex for every block in the LRU list. Only acquire
      it when holding buf_pool_mutex is not sufficient. This should speed up
      the function and considerably reduce traffic on the memory bus and
      caches.
      
      I noticed this deficiency when working on Issue #157.
      This deficiency popped up again in Issue #449 (Bug #35077),
      which this fix does not fully address.
      
      rb://78 revision 1 approved by Heikki Tuuri.

    modified:
      storage/innodb_plugin/buf/buf0lru.c
=== modified file 'storage/innodb_plugin/buf/buf0lru.c'
--- a/storage/innodb_plugin/buf/buf0lru.c	2009-11-03 10:26:07 +0000
+++ b/storage/innodb_plugin/buf/buf0lru.c	2010-04-01 11:27:18 +0000
@@ -347,20 +347,34 @@ scan_again:
 
 	all_freed = TRUE;
 
+rescan:
 	bpage = UT_LIST_GET_LAST(buf_pool->LRU);
 
 	while (bpage != NULL) {
-		mutex_t*	block_mutex = buf_page_get_mutex(bpage);
 		buf_page_t*	prev_bpage;
 
 		ut_a(buf_page_in_file(bpage));
 
-		mutex_enter(block_mutex);
 		prev_bpage = UT_LIST_GET_PREV(LRU, bpage);
 
-		if (buf_page_get_space(bpage) == id) {
-			if (bpage->buf_fix_count > 0
-			    || buf_page_get_io_fix(bpage) != BUF_IO_NONE) {
+		/* bpage->space and bpage->io_fix are protected by
+		buf_pool_mutex and block_mutex.  It is safe to check
+		them while holding buf_pool_mutex only. */
+
+		if (buf_page_get_space(bpage) != id) {
+			/* Skip this block, as it does not belong to
+			the space that is being invalidated. */
+		} else if (buf_page_get_io_fix(bpage) != BUF_IO_NONE) {
+			/* We cannot remove this page during this scan
+			yet; maybe the system is currently reading it
+			in, or flushing the modifications to the file */
+
+			all_freed = FALSE;
+		} else {
+			mutex_t* block_mutex = buf_page_get_mutex(bpage);
+			mutex_enter(block_mutex);
+
+			if (bpage->buf_fix_count > 0) {
 
 				/* We cannot remove this page during
 				this scan yet; maybe the system is
@@ -423,12 +437,12 @@ scan_again:
 				buf_buddy_free() may have relocated
 				prev_bpage.  Rescan the LRU list. */
 
-				bpage = UT_LIST_GET_LAST(buf_pool->LRU);
-				continue;
+				goto rescan;
 			}
-		}
 next_page:
-		mutex_exit(block_mutex);
+			mutex_exit(block_mutex);
+		}
+
 		bpage = prev_bpage;
 	}
 


Attachment: [text/bzr-bundle] bzr/[e-mail]