Merge lp:~akopytov/percona-server/bug1125259 into lp:percona-server/5.5

[Alexey Kopytov]

Bug #1125259: srv_pass_corrupt_table can share the cache line with row
                  counters

    The place where srv_pass_corrupt_table (and a few other variables) was
    declared in srv0srv.c might become an infinite source of false sharing due
    to their proximity to row counters.

    Fixed by grouping and aligning all counters properly to ensure they are
    on separate cache lines and never share lines with other variables.

[Alexey Kopytov (akopytov)]

http://jenkins.percona.com/view/PS%205.5/job/percona-server-5.5-param/674/

[Stewart Smith (stewart)]

review: Approve

=== modified file 'Percona-Server/storage/innobase/srv/srv0srv.c'
--- Percona-Server/storage/innobase/srv/srv0srv.c	2013-02-13 20:31:43 +0000
+++ Percona-Server/storage/innobase/srv/srv0srv.c	2013-02-17 09:43:26 +0000
@@ -312,58 +312,11 @@
 /* the number of rollback segments to use */
 UNIV_INTERN ulong srv_rollback_segments = TRX_SYS_N_RSEGS;
 
-/* variable counts amount of data read in total (in bytes) */
-UNIV_INTERN ulint srv_data_read = 0;
-
 /* Internal setting for "innodb_stats_method". Decides how InnoDB treats
 NULL value when collecting statistics. By default, it is set to
 SRV_STATS_NULLS_EQUAL(0), ie. all NULL value are treated equal */
 ulong srv_innodb_stats_method = SRV_STATS_NULLS_EQUAL;
 
-/* here we count the amount of data written in total (in bytes) */
-UNIV_INTERN ulint srv_data_written = 0;
-
-/* the number of the log write requests done */
-UNIV_INTERN ulint srv_log_write_requests = 0;
-
-/* the number of physical writes to the log performed */
-UNIV_INTERN ulint srv_log_writes = 0;
-
-/* amount of data written to the log files in bytes */
-UNIV_INTERN ulint srv_os_log_written = 0;
-
-/* amount of writes being done to the log files */
-UNIV_INTERN ulint srv_os_log_pending_writes = 0;
-
-/* we increase this counter, when there we don't have enough space in the
-log buffer and have to flush it */
-UNIV_INTERN ulint srv_log_waits = 0;
-
-/* this variable counts the amount of times, when the doublewrite buffer
-was flushed */
-UNIV_INTERN ulint srv_dblwr_writes = 0;
-
-/* here we store the number of pages that have been flushed to the
-doublewrite buffer */
-UNIV_INTERN ulint srv_dblwr_pages_written = 0;
-
-/* in this variable we store the number of write requests issued */
-UNIV_INTERN ulint srv_buf_pool_write_requests = 0;
-
-/* here we store the number of times when we had to wait for a free page
-in the buffer pool. It happens when the buffer pool is full and we need
-to make a flush, in order to be able to read or create a page. */
-UNIV_INTERN ulint srv_buf_pool_wait_free = 0;
-
-/* variable to count the number of pages that were written from buffer
-pool to the disk */
-UNIV_INTERN ulint srv_buf_pool_flushed = 0;
-UNIV_INTERN ulint buf_lru_flush_page_count = 0;
-
-/** Number of buffer pool reads that led to the
-reading of a disk page */
-UNIV_INTERN ulint srv_buf_pool_reads = 0;
-
 /** Time in seconds between automatic buffer pool dumps */
 UNIV_INTERN uint srv_auto_lru_dump = 0;
 
@@ -489,23 +442,83 @@
 UNIV_INTERN ibool	srv_print_latch_waits		= FALSE;
 #endif /* UNIV_DEBUG */
 
-UNIV_INTERN ulint		srv_n_rows_inserted		= 0;
-UNIV_INTERN ulint		srv_n_rows_updated		= 0;
-UNIV_INTERN ulint		srv_n_rows_deleted		= 0;
-UNIV_INTERN ulint		srv_n_rows_read			= 0;
-
 static ulint	srv_n_rows_inserted_old		= 0;
 static ulint	srv_n_rows_updated_old		= 0;
 static ulint	srv_n_rows_deleted_old		= 0;
 static ulint	srv_n_rows_read_old		= 0;
 
-UNIV_INTERN ulint		srv_n_lock_deadlock_count	= 0;
-UNIV_INTERN ulint		srv_n_lock_wait_count		= 0;
-UNIV_INTERN ulint		srv_n_lock_wait_current_count	= 0;
-UNIV_INTERN ib_int64_t	srv_n_lock_wait_time		= 0;
-UNIV_INTERN ulint		srv_n_lock_max_wait_time	= 0;
-
-UNIV_INTERN ulint		srv_truncated_status_writes	= 0;
+/* Ensure counters are on separate cache lines */
+
+#define CACHE_LINE_SIZE 64
+#define CACHE_ALIGNED __attribute__ ((aligned (CACHE_LINE_SIZE)))
+
+UNIV_INTERN byte
+counters_pad_start[CACHE_LINE_SIZE] __attribute__((unused)) = {0};
+
+UNIV_INTERN ulint		srv_n_rows_inserted CACHE_ALIGNED	= 0;
+UNIV_INTERN ulint		srv_n_rows_updated CACHE_ALIGNED	= 0;
+UNIV_INTERN ulint		srv_n_rows_deleted CACHE_ALIGNED	= 0;
+UNIV_INTERN ulint		srv_n_rows_read CACHE_ALIGNED		= 0;
+
+UNIV_INTERN ulint		srv_n_lock_deadlock_count CACHE_ALIGNED	= 0;
+UNIV_INTERN ulint		srv_n_lock_wait_count CACHE_ALIGNED	= 0;
+UNIV_INTERN ulint		srv_n_lock_wait_current_count CACHE_ALIGNED = 0;
+UNIV_INTERN ib_int64_t	srv_n_lock_wait_time CACHE_ALIGNED		= 0;
+UNIV_INTERN ulint		srv_n_lock_max_wait_time CACHE_ALIGNED	= 0;
+
+UNIV_INTERN ulint		srv_truncated_status_writes CACHE_ALIGNED = 0;
+
+/* variable counts amount of data read in total (in bytes) */
+UNIV_INTERN ulint srv_data_read CACHE_ALIGNED			= 0;
+
+/* here we count the amount of data written in total (in bytes) */
+UNIV_INTERN ulint srv_data_written CACHE_ALIGNED		= 0;
+
+/* the number of the log write requests done */
+UNIV_INTERN ulint srv_log_write_requests CACHE_ALIGNED		= 0;
+
+/* the number of physical writes to the log performed */
+UNIV_INTERN ulint srv_log_writes CACHE_ALIGNED			= 0;
+
+/* amount of data written to the log files in bytes */
+UNIV_INTERN ulint srv_os_log_written CACHE_ALIGNED		= 0;
+
+/* amount of writes being done to the log files */
+UNIV_INTERN ulint srv_os_log_pending_writes CACHE_ALIGNED	= 0;
+
+/* we increase this counter, when there we don't have enough space in the
+log buffer and have to flush it */
+UNIV_INTERN ulint srv_log_waits CACHE_ALIGNED			= 0;
+
+/* this variable counts the amount of times, when the doublewrite buffer
+was flushed */
+UNIV_INTERN ulint srv_dblwr_writes CACHE_ALIGNED		= 0;
+
+/* here we store the number of pages that have been flushed to the
+doublewrite buffer */
+UNIV_INTERN ulint srv_dblwr_pages_written CACHE_ALIGNED		= 0;
+
+/* in this variable we store the number of write requests issued */
+UNIV_INTERN ulint srv_buf_pool_write_requests CACHE_ALIGNED	= 0;
+
+/* here we store the number of times when we had to wait for a free page
+in the buffer pool. It happens when the buffer pool is full and we need
+to make a flush, in order to be able to read or create a page. */
+UNIV_INTERN ulint srv_buf_pool_wait_free CACHE_ALIGNED		= 0;
+
+/** Number of buffer pool reads that led to the
+reading of a disk page */
+UNIV_INTERN ulint srv_buf_pool_reads CACHE_ALIGNED		= 0;
+
+/* variable to count the number of pages that were written from buffer
+pool to the disk */
+UNIV_INTERN ulint srv_buf_pool_flushed CACHE_ALIGNED		= 0;
+
+/* variable to count the number of LRU flushed pages */
+UNIV_INTERN ulint buf_lru_flush_page_count CACHE_ALIGNED	= 0;
+
+UNIV_INTERN byte
+counters_pad_end[CACHE_LINE_SIZE] __attribute__((unused)) = {0};
 
 /*
   Set the following to 0 if you want InnoDB to write messages on