Remove the mandatory work requirement at startup by testing for invalid work being passed which allows for work to be queued immediately.

This also removes the requirement for resetting the timecodes at the start which caused huge over-estimates of hashing for a short period.

main.c

@@ -2035,7 +2035,8 @@ static void flush_requests(void)
 
 static inline bool can_roll(struct work *work)
 {
-	return (!stale_work(work) && work->pool->has_rolltime && work->rolls < 11);
+	return (work->pool && !stale_work(work) && work->pool->has_rolltime &&
+		work->rolls < 11);
 }
 
 static bool get_work(struct work *work, bool queued, struct thr_info *thr,
@@ -2179,6 +2180,7 @@ bool submit_nonce(struct thr_info *thr, struct work *work, uint32_t nonce)
 
 static void *miner_thread(void *userdata)
 {
+	struct work work __attribute__((aligned(128)));
 	struct thr_info *mythr = userdata;
 	const int thr_id = mythr->id;
 	uint32_t max_nonce = 0xffffff, total_hashes = 0;
@@ -2205,8 +2207,10 @@ static void *miner_thread(void *userdata)
 	if (!(opt_n_threads % num_processors))
 		affine_to_cpu(thr_id - gpu_threads, dev_from_id(thr_id));
 
+	/* Invalidate pool so it fails can_roll() test */
+	work.pool = NULL;
+
 	while (1) {
-		struct work work __attribute__((aligned(128)));
 		struct timeval tv_workstart, tv_start, tv_end, diff;
 		uint64_t max64;
 		bool rc;
@@ -2477,6 +2481,8 @@ static void *gpuminer_thread(void *userdata)
 	diff.tv_sec = 0;
 	gettimeofday(&tv_end, NULL);
 
+	work->pool = NULL;
+
 	status = clEnqueueWriteBuffer(clState->commandQueue, clState->outputBuffer, CL_TRUE, 0,
 			BUFFERSIZE, blank_res, 0, NULL, NULL);
 	if (unlikely(status != CL_SUCCESS))
@@ -3323,10 +3329,6 @@ int main (int argc, char *argv[])
 		quit(1, "stage thread create failed");
 	pthread_detach(thr->pth);
 
-	/* Flag the work as ready forcing the mining threads to wait till we
-	 * actually put something into the queue */
-	inc_staged(current_pool(), mining_threads, true);
-
 	/* Create a unique get work queue */
 	getq = tq_new();
 	if (!getq)
@@ -3433,13 +3435,6 @@ int main (int argc, char *argv[])
 	if (pthread_create(&thr->pth, NULL, watchdog_thread, NULL))
 		quit(1, "wakeup thread create failed");
 
-	/* Restart count as it will be wrong till all threads are started */
-	pthread_mutex_lock(&hash_lock);
-	gettimeofday(&total_tv_start, NULL);
-	gettimeofday(&total_tv_end, NULL);
-	total_mhashes_done = 0;
-	pthread_mutex_unlock(&hash_lock);
-
 	/* Now that everything's ready put enough work in the queue */
 	for (i = 0; i < opt_queue + mining_threads; i++) {
 		if (unlikely(!queue_request()))