[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/gettime.c b/gettime.c
new file mode 100644
index 0000000..48aeb07
--- /dev/null
+++ b/gettime.c
@@ -0,0 +1,135 @@
+/*
+ * Memory helpers
+ */
+#include <unistd.h>
+#include <sys/time.h>
+
+#include "fio.h"
+#include "os.h"
+
+#include "hash.h"
+
+static int clock_gettime_works = 1;
+
+#ifdef FIO_DEBUG_TIME
+
+#define HASH_BITS 8
+#define HASH_SIZE (1 << HASH_BITS)
+
+static struct list_head hash[HASH_SIZE];
+static int gtod_inited;
+
+struct gtod_log {
+ struct list_head list;
+ void *caller;
+ unsigned long calls;
+};
+
+static struct gtod_log *find_hash(void *caller)
+{
+ unsigned long h = hash_ptr(caller, HASH_BITS);
+ struct list_head *entry;
+
+ list_for_each(entry, &hash[h]) {
+ struct gtod_log *log = list_entry(entry, struct gtod_log, list);
+
+ if (log->caller == caller)
+ return log;
+ }
+
+ return NULL;
+}
+
+static struct gtod_log *find_log(void *caller)
+{
+ struct gtod_log *log = find_hash(caller);
+
+ if (!log) {
+ unsigned long h;
+
+ log = malloc(sizeof(*log));
+ INIT_LIST_HEAD(&log->list);
+ log->caller = caller;
+ log->calls = 0;
+
+ h = hash_ptr(caller, HASH_BITS);
+ list_add_tail(&log->list, &hash[h]);
+ }
+
+ return log;
+}
+
+static void gtod_log_caller(void *caller)
+{
+ if (gtod_inited) {
+ struct gtod_log *log = find_log(caller);
+
+ log->calls++;
+ }
+}
+
+static void fio_exit fio_dump_gtod(void)
+{
+ unsigned long total_calls = 0;
+ int i;
+
+ for (i = 0; i < HASH_SIZE; i++) {
+ struct list_head *entry;
+ struct gtod_log *log;
+
+ list_for_each(entry, &hash[i]) {
+ log = list_entry(entry, struct gtod_log, list);
+
+ printf("function %p, calls %lu\n", log->caller, log->calls);
+ total_calls += log->calls;
+ }
+ }
+
+ printf("Total %lu gettimeofday\n", total_calls);
+}
+
+static void fio_init gtod_init(void)
+{
+ int i;
+
+ for (i = 0; i < HASH_SIZE; i++)
+ INIT_LIST_HEAD(&hash[i]);
+
+ gtod_inited = 1;
+}
+
+#endif /* FIO_DEBUG_TIME */
+
+void fio_gettime(struct timeval *tp, void *caller)
+{
+#ifdef FIO_DEBUG_TIME
+ if (!caller)
+ caller = __builtin_return_address(0);
+
+ gtod_log_caller(caller);
+#else
+ caller = NULL;
+#endif
+repeat:
+ if (!clock_gettime_works)
+ gettimeofday(tp, NULL);
+ else {
+ struct timespec ts;
+
+ if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
+ clock_gettime_works = 0;
+ goto repeat;
+ }
+
+ tp->tv_sec = ts.tv_sec;
+ tp->tv_usec = ts.tv_nsec / 1000;
+ }
+}
+
+static void fio_init check_clock(void)
+{
+ struct timespec ts;
+
+ if (clock_getres(CLOCK_MONOTONIC, &ts) < 0)
+ clock_gettime_works = 0;
+}