[PATCH] Time and seek optimizations

We did too many gettimeofday() calls, this patch cuts the number by
40%. Use clock_gettime() MONOTONIC instead, it is faster on my system
at least.

This patch also optimizes calling lseek() only when necessary for the
sync io engine.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index faa06a4..cb78f25 100644
--- a/fio.h
+++ b/fio.h
@@ -156,6 +156,7 @@
 	unsigned long long real_file_size;
 	unsigned long long file_offset;
 	unsigned long long last_pos;
+	unsigned long long last_completed_pos;
 
 	unsigned long *file_map;
 	unsigned int num_maps;
@@ -410,6 +411,7 @@
 
 	int error;			/* output */
 	unsigned long bytes_done[2];	/* output */
+	struct timeval time;		/* output */
 };
 
 #define DISK_UTIL_MSEC	(250)
@@ -436,7 +438,7 @@
  */
 extern void add_clat_sample(struct thread_data *, int, unsigned long);
 extern void add_slat_sample(struct thread_data *, int, unsigned long);
-extern void add_bw_sample(struct thread_data *, int);
+extern void add_bw_sample(struct thread_data *, int, struct timeval *);
 extern void show_run_stats(void);
 extern void init_disk_util(struct thread_data *);
 extern void update_rusage_stat(struct thread_data *);
@@ -449,7 +451,6 @@
 /*
  * Time functions
  */
-extern void time_init(void);
 extern unsigned long utime_since(struct timeval *, struct timeval *);
 extern unsigned long mtime_since(struct timeval *, struct timeval *);
 extern unsigned long mtime_since_now(struct timeval *);
@@ -459,6 +460,7 @@
 extern void usec_sleep(struct thread_data *, unsigned long);
 extern void rate_throttle(struct thread_data *, unsigned long, unsigned int, int);
 extern void fill_start_time(struct timeval *);
+extern void fio_gettime(struct timeval *, void *);
 
 /*
  * Init functions