/*
* test_fsync.c
- * tests if fsync can be done from another process than the original write
+ * test various fsync() methods
*/
-#include "../../include/pg_config.h"
-#include "../../include/pg_config_os.h"
+#include "postgres.h"
+
+#include "access/xlog_internal.h"
+#include "access/xlog.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
+#include <string.h>
-#ifdef WIN32
-#define FSYNC_FILENAME "./test_fsync.out"
+/* ---------------------------------------------------------------
+ * Copied from xlog.c. Some day this should be moved an include file.
+ */
+
+/*
+ * Because O_DIRECT bypasses the kernel buffers, and because we never
+ * read those buffers except during crash recovery, it is a win to use
+ * it in all cases where we sync on each write(). We could allow O_DIRECT
+ * with fsync(), but because skipping the kernel buffer forces writes out
+ * quickly, it seems best just to use it for O_SYNC. It is hard to imagine
+ * how fsync() could be a win for O_DIRECT compared to O_SYNC and O_DIRECT.
+ * Also, O_DIRECT is never enough to force data to the drives, it merely
+ * tries to bypass the kernel cache, so we still need O_SYNC or fsync().
+ */
+#ifdef O_DIRECT
+#define PG_O_DIRECT O_DIRECT
#else
-#define FSYNC_FILENAME "/var/tmp/test_fsync.out"
+#define PG_O_DIRECT 0
#endif
-/* O_SYNC and O_FSYNC are the same */
+/*
+ * This chunk of hackery attempts to determine which file sync methods
+ * are available on the current platform, and to choose an appropriate
+ * default method. We assume that fsync() is always available, and that
+ * configure determined whether fdatasync() is.
+ */
#if defined(O_SYNC)
-#define OPEN_SYNC_FLAG O_SYNC
+#define BARE_OPEN_SYNC_FLAG O_SYNC
#elif defined(O_FSYNC)
-#define OPEN_SYNC_FLAG O_FSYNC
-#elif defined(O_DSYNC)
-#define OPEN_DATASYNC_FLAG O_DSYNC
+#define BARE_OPEN_SYNC_FLAG O_FSYNC
+#endif
+#ifdef BARE_OPEN_SYNC_FLAG
+#define OPEN_SYNC_FLAG (BARE_OPEN_SYNC_FLAG | PG_O_DIRECT)
#endif
+#if defined(O_DSYNC)
#if defined(OPEN_SYNC_FLAG)
-#if defined(O_DSYNC) && (O_DSYNC != OPEN_SYNC_FLAG)
-#define OPEN_DATASYNC_FLAG O_DSYNC
+/* O_DSYNC is distinct? */
+#if O_DSYNC != BARE_OPEN_SYNC_FLAG
+#define OPEN_DATASYNC_FLAG (O_DSYNC | PG_O_DIRECT)
+#endif
+#else /* !defined(OPEN_SYNC_FLAG) */
+/* Win32 only has O_DSYNC */
+#define OPEN_DATASYNC_FLAG (O_DSYNC | PG_O_DIRECT)
+#endif
+#endif
+
+#if defined(OPEN_DATASYNC_FLAG)
+#define DEFAULT_SYNC_METHOD_STR "open_datasync"
+#define DEFAULT_SYNC_METHOD SYNC_METHOD_OPEN
+#define DEFAULT_SYNC_FLAGBIT OPEN_DATASYNC_FLAG
+#elif defined(HAVE_FDATASYNC)
+#define DEFAULT_SYNC_METHOD_STR "fdatasync"
+#define DEFAULT_SYNC_METHOD SYNC_METHOD_FDATASYNC
+#define DEFAULT_SYNC_FLAGBIT 0
+#elif defined(HAVE_FSYNC_WRITETHROUGH_ONLY)
+#define DEFAULT_SYNC_METHOD_STR "fsync_writethrough"
+#define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC_WRITETHROUGH
+#define DEFAULT_SYNC_FLAGBIT 0
+#else
+#define DEFAULT_SYNC_METHOD_STR "fsync"
+#define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC
+#define DEFAULT_SYNC_FLAGBIT 0
+#endif
+
+
+/*
+ * Limitation of buffer-alignment for direct IO depends on OS and filesystem,
+ * but XLOG_BLCKSZ is assumed to be enough for it.
+ */
+#ifdef O_DIRECT
+#define ALIGNOF_XLOG_BUFFER XLOG_BLCKSZ
+#else
+#define ALIGNOF_XLOG_BUFFER ALIGNOF_BUFFER
#endif
+
+/* ------------ from xlog.c --------------- */
+
+#ifdef WIN32
+#define FSYNC_FILENAME "./test_fsync.out"
+#else
+/* /tmp might be a memory file system */
+#define FSYNC_FILENAME "/var/tmp/test_fsync.out"
#endif
-#define WAL_FILE_SIZE (16 * 1024 * 1024)
+#define WRITE_SIZE (16 * 1024)
void die(char *str);
void print_elapse(struct timeval start_t, struct timeval elapse_t);
int tmpfile,
i,
loops = 1000;
- char *strout = (char *) malloc(WAL_FILE_SIZE);
+ char *full_buf = (char *) malloc(XLOG_SEG_SIZE), *buf;
char *filename = FSYNC_FILENAME;
if (argc > 2 && strcmp(argv[1], "-f") == 0)
if (argc > 1)
loops = atoi(argv[1]);
- for (i = 0; i < WAL_FILE_SIZE; i++)
- strout[i] = 'a';
+ for (i = 0; i < XLOG_SEG_SIZE; i++)
+ full_buf[i] = 'a';
if ((tmpfile = open(filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR)) == -1)
die("Cannot open output file.");
- write(tmpfile, strout, WAL_FILE_SIZE);
- fsync(tmpfile); /* fsync so later fsync's don't have to do it */
+ if (write(tmpfile, full_buf, XLOG_SEG_SIZE) != XLOG_SEG_SIZE)
+ die("write failed");
+ /* fsync so later fsync's don't have to do it */
+ if (fsync(tmpfile) != 0)
+ die("fsync failed");
close(tmpfile);
+ buf = (char *)TYPEALIGN(ALIGNOF_XLOG_BUFFER, full_buf);
+
printf("Simple write timing:\n");
/* write only */
gettimeofday(&start_t, NULL);
{
if ((tmpfile = open(filename, O_RDWR)) == -1)
die("Cannot open output file.");
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
close(tmpfile);
}
gettimeofday(&elapse_t, NULL);
{
if ((tmpfile = open(filename, O_RDWR)) == -1)
die("Cannot open output file.");
- write(tmpfile, strout, 8192);
- fsync(tmpfile);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (fsync(tmpfile) != 0)
+ die("fsync failed");
close(tmpfile);
if ((tmpfile = open(filename, O_RDWR)) == -1)
die("Cannot open output file.");
{
if ((tmpfile = open(filename, O_RDWR)) == -1)
die("Cannot open output file.");
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
close(tmpfile);
/* reopen file */
if ((tmpfile = open(filename, O_RDWR)) == -1)
die("Cannot open output file.");
- fsync(tmpfile);
+ if (fsync(tmpfile) != 0)
+ die("fsync failed");
close(tmpfile);
}
gettimeofday(&elapse_t, NULL);
die("Cannot open output file.");
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
- write(tmpfile, strout, 16384);
+ if (write(tmpfile, buf, WRITE_SIZE) != WRITE_SIZE)
+ die("write failed");
gettimeofday(&elapse_t, NULL);
close(tmpfile);
printf("\tone 16k o_sync write ");
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
}
gettimeofday(&elapse_t, NULL);
close(tmpfile);
die("Cannot open output file.");
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
gettimeofday(&elapse_t, NULL);
close(tmpfile);
printf("\topen o_dsync, write ");
die("Cannot open output file.");
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
gettimeofday(&elapse_t, NULL);
close(tmpfile);
printf("\topen o_sync, write ");
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
fdatasync(tmpfile);
}
gettimeofday(&elapse_t, NULL);
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
- fsync(tmpfile);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (fsync(tmpfile) != 0)
+ die("fsync failed");
}
gettimeofday(&elapse_t, NULL);
close(tmpfile);
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
}
gettimeofday(&elapse_t, NULL);
close(tmpfile);
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
}
gettimeofday(&elapse_t, NULL);
close(tmpfile);
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
- write(tmpfile, strout, 8192);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
fdatasync(tmpfile);
}
gettimeofday(&elapse_t, NULL);
gettimeofday(&start_t, NULL);
for (i = 0; i < loops; i++)
{
- write(tmpfile, strout, 8192);
- write(tmpfile, strout, 8192);
- fsync(tmpfile);
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (write(tmpfile, buf, WRITE_SIZE/2) != WRITE_SIZE/2)
+ die("write failed");
+ if (fsync(tmpfile) != 0)
+ die("fsync failed");
}
gettimeofday(&elapse_t, NULL);
close(tmpfile);
print_elapse(start_t, elapse_t);
printf("\n");
+ free(full_buf);
unlink(filename);
return 0;
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