Merge lp:~sergei.glushchenko/percona-xtrabackup/2.0-xb-bug1093385 into lp:percona-xtrabackup/2.0

[Sergei Glushchenko]

This patch makes posix_fadvise to specify ranges. This reduces IO done to make a backup.
My experiment showed that bytes read needed to copy 886M database reduced from 980M to 886M. I also checked that datafiles are not cached upon backup done and during the backup.
Since POSIX_FADV_DONTNEED on Linux works only for data already in cache I removed posix_fadvise(dst_file, 0, 0, POSIX_FADV_DONTNEED) invocations upon file opening since we may benefit from data already in cache.

http://jenkins.percona.com/view/PXB%202.0/job/percona-xtrabackup-2.0-param/516/

failure on innodb56 seems to be unrelated to patch.

[Alexey Kopytov (akopytov)]

review: Approve

=== modified file 'src/xbstream.c'
--- src/xbstream.c	2013-08-18 06:53:11 +0000
+++ src/xbstream.c	2014-02-25 17:09:23 +0000
@@ -199,9 +199,13 @@
 {
 	uchar	buf[XBSTREAM_BUFFER_SIZE];
 	size_t	bytes;
+#ifdef USE_POSIX_FADVISE
+	size_t	offset;
+#endif
 
 #ifdef USE_POSIX_FADVISE
 	posix_fadvise(file, 0, 0, POSIX_FADV_SEQUENTIAL);
+	offset = my_tell(file, MYF(MY_WME));
 #endif
 
 	while ((bytes = my_read(file, buf, XBSTREAM_BUFFER_SIZE,
@@ -212,7 +216,9 @@
 			return 1;
 		}
 #ifdef USE_POSIX_FADVISE
-		posix_fadvise(file, 0, 0, POSIX_FADV_DONTNEED);
+		posix_fadvise(file, offset, XBSTREAM_BUFFER_SIZE,
+			      POSIX_FADV_DONTNEED);
+		offset += XBSTREAM_BUFFER_SIZE;
 #endif
 
 	}
 
=== modified file 'src/xtrabackup.cc'
--- src/xtrabackup.cc	2013-11-05 09:54:40 +0000
+++ src/xtrabackup.cc	2014-02-25 17:09:23 +0000
@@ -4285,7 +4285,7 @@
 		}
 
 #ifdef USE_POSIX_FADVISE
-		posix_fadvise(node->handle, 0, 0, POSIX_FADV_DONTNEED);
+		posix_fadvise(node->handle, offset, chunk, POSIX_FADV_DONTNEED);
 #endif
 
 		/* check corruption and retry */
@@ -5104,6 +5104,9 @@
 	uchar		*buf = NULL;
 	const size_t	buf_size = 1024 * 1024;
 	size_t		bytes;
+#ifdef USE_POSIX_FADVISE
+	size_t		offset;
+#endif
 	ds_file_t	*dst_file = NULL;
 	MY_STAT		mystat;
 
@@ -5133,9 +5136,13 @@
 
 	buf = (uchar *) ut_malloc(buf_size);
 
+#ifdef USE_POSIX_FADVISE
+	offset = 0;
+#endif
+
 	while ((bytes = my_read(src_file, buf, buf_size, MYF(MY_WME))) > 0) {
 #ifdef USE_POSIX_FADVISE
-		posix_fadvise(src_file, 0, 0, POSIX_FADV_DONTNEED);
+		posix_fadvise(src_file, offset, buf_size, POSIX_FADV_DONTNEED);
 #endif
 		if (ds->write(dst_file, buf, bytes)) {
 			msg("xtrabackup: error: cannot write to stream "
@@ -7091,6 +7098,8 @@
 	byte*		incremental_buffer_base = NULL;
 	byte*		incremental_buffer;
 
+	size_t		offset;
+
 	ut_a(xtrabackup_incremental);
 
 	if (dbname) {
@@ -7143,7 +7152,6 @@
 
 #ifdef USE_POSIX_FADVISE
 	posix_fadvise(src_file, 0, 0, POSIX_FADV_SEQUENTIAL);
-	posix_fadvise(src_file, 0, 0, POSIX_FADV_DONTNEED);
 #endif
 
 	xb_file_set_nocache(src_file, src_path, "OPEN");
@@ -7156,10 +7164,6 @@
 		goto error;
 	}
 
-#ifdef USE_POSIX_FADVISE
-	posix_fadvise(dst_file, 0, 0, POSIX_FADV_DONTNEED);
-#endif
-
 	xb_file_set_nocache(dst_file, dst_path, "OPEN");
 
 	/* allocate buffer for incremental backup (4096 pages) */
@@ -7177,11 +7181,10 @@
 
 		/* read to buffer */
 		/* first block of block cluster */
+		offset = ((incremental_buffers * (page_size / 4))
+			 << page_size_shift);
 		success = xb_os_file_read(src_file, incremental_buffer,
-					  ((incremental_buffers
-					    * (page_size / 4))
-					   << page_size_shift),
-					  page_size);
+					  offset, page_size);
 		if (!success) {
 			goto error;
 		}
@@ -7210,14 +7213,16 @@
 
 		/* read whole of the cluster */
 		success = xb_os_file_read(src_file, incremental_buffer,
-					  ((incremental_buffers
-					    * (page_size / 4))
-					   << page_size_shift),
-					  page_in_buffer * page_size);
+					  offset, page_in_buffer * page_size);
 		if (!success) {
 			goto error;
 		}
 
+#ifdef USE_POSIX_FADVISE
+		posix_fadvise(src_file, offset, page_in_buffer * page_size,
+			      POSIX_FADV_DONTNEED);
+#endif
+
 		for (page_in_buffer = 1; page_in_buffer < page_size / 4;
 		     page_in_buffer++) {
 			ulint offset_on_page;
@@ -7242,6 +7247,9 @@
 			if (!success) {
 				goto error;
 			}
+#ifdef USE_POSIX_FADVISE
+			posix_fadvise(dst_file, 0, 0, POSIX_FADV_DONTNEED);
+#endif
 		}
 
 		incremental_buffers++;