Add fsync test program. It tests fsync to see if times for fsync are the

same when done on the write() ile descriptor and a new descriptor.

it also times various fsync methods.

src/tools/fsync/Makefile

+#
+# Makefile
+#
+#
+TARGET = test_fsync
+XFLAGS = 
+CFLAGS = -g -Wall
+LIBS = 
+
+$(TARGET) : test_fsync.o
+	$(CC) -o $(TARGET) $(XFLAGS) $(CFLAGS) test_fsync.o $(LIBS)
+
+test_fsync.o	: test_fsync.c 
+	$(CC) -c $(XFLAGS) $(CFLAGS) test_fsync.c
+
+clean:
+	rm -f *.o $(TARGET) log core
+
+install:
+	make clean
+	make CFLAGS=-O
+	install -s -o bin -g bin $(TARGET) /usr/local/bin

src/tools/fsync/README

+This program tests fsync.  If first times a simple read.  Then, it times
+an fsync that is part of a write, and one that is done on a newly opened
+file.  Third, it tests various fsync methods.
+
+The program writes to /var/tmp because /tmp is sometimes a memory file
+system.
+

src/tools/fsync/test_fsync.c

+/*
+ *	test_fsync.c
+ *		tests if fsync can be done from another process than the original write
+ */
+
+#include "../../include/pg_config.h"
+
+#include <sys/types.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+
+/* O_SYNC and O_FSYNC are the same */
+#if defined(O_SYNC)
+#define OPEN_SYNC_FLAG		O_SYNC
+#elif defined(O_FSYNC)
+#define OPEN_SYNC_FLAG		O_FSYNC
+#endif
+
+#if defined(OPEN_SYNC_FLAG)
+#if defined(O_DSYNC) && (O_DSYNC != OPEN_SYNC_FLAG)
+#define OPEN_DATASYNC_FLAG	O_DSYNC
+#endif
+#endif
+
+void die(char *str);
+void print_elapse(struct timeval start_t, struct timeval elapse_t);
+
+int main(int argc, char *argv[])
+{
+	struct timeval start_t;
+	struct timeval elapse_t;
+	int tmpfile;
+	char *strout = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+
+	printf("Simple write timing:\n");
+	/* write only */	
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	close(tmpfile);		
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("write                  ");
+	print_elapse(start_t, elapse_t);
+	printf("\n\n");
+
+	printf("Compare fsync before and after write's close:\n");
+	/* write, fsync, close */
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	fsync(tmpfile);
+	close(tmpfile);		
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("write, fsync, close    ");
+	print_elapse(start_t, elapse_t);
+	printf("\n");
+
+	/* write, close, fsync */
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	close(tmpfile);
+	/* reopen file */
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	fsync(tmpfile);
+	close(tmpfile);		
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("write, close, fsync    ");
+	print_elapse(start_t, elapse_t);
+	printf("\n");
+
+	printf("\nTest file sync methods\n");
+
+#ifdef OPEN_DATASYNC_FLAG
+	/* open_dsync, write */
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT | O_DSYNC)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	close(tmpfile);
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("open o_dsync, write    ");
+	print_elapse(start_t, elapse_t);
+	printf("\n");
+#endif
+
+	/* open_fsync, write */
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT | OPEN_SYNC_FLAG)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	close(tmpfile);
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("open o_fsync, write    ");
+	print_elapse(start_t, elapse_t);
+	printf("\n");
+
+#ifdef HAVE_FDATASYNC
+	/* write, fdatasync */
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	fdatasync(tmpfile);
+	close(tmpfile);
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("write, fdatasync       ");
+	print_elapse(start_t, elapse_t);
+	printf("\n");
+#endif
+
+	/* write, fsync, close */
+	gettimeofday(&start_t, NULL);
+	if ((tmpfile = open("/var/tmp/test_fsync.out", O_RDWR | O_CREAT)) == -1)
+		die("can't open /var/tmp/test_fsync.out");
+	write(tmpfile, &strout, 200);
+	fsync(tmpfile);
+	close(tmpfile);
+	gettimeofday(&elapse_t, NULL);
+	unlink("/var/tmp/test_fsync.out");
+	printf("write, fsync,          ");
+	print_elapse(start_t, elapse_t);
+	printf("\n");
+
+	return 0;
+}
+
+void print_elapse(struct timeval start_t, struct timeval elapse_t)
+{
+	if (elapse_t.tv_usec < start_t.tv_usec)
+	{
+		elapse_t.tv_sec--;
+		elapse_t.tv_usec += 1000000;
+	}
+
+	printf("%ld.%06ld", (long) (elapse_t.tv_sec - start_t.tv_sec),
+					 (long) (elapse_t.tv_usec - start_t.tv_usec));
+}
+
+void die(char *str)
+{
+	fprintf(stderr, "%s", str);
+	exit(1);
+}