Add automated benchmark of the CPU hashers

    The --algo switch now accepts the "auto" argument.

    When "auto" is passed to --algo, cgminer starts by benchmarking
    all the CPU algorithms it nows about and picks the fastest.

    This is useful for benchmarking, but also for folks who run
    cgminer on a large number of heterogeneous computers because
    it saves them from having to configure each instance optimally.

    Caveat emptor: depending on the platform, some algorithms will
    fail with "illegal instruction" (e.g. via padlock code on non via
    platforms, or SSE4 code on non SSE4 platforms).

    To protect against this, cgminer runs the benchmarks in a child
    process. The crash, if any occurs in the child, and the parent
    marks this algo as "fails" and continues benchmarking the next
    algorithm.

    Unfortunately, this safeguard is only implemented for Linux
    because I have no clue how to do this on win32 (nor access to
    a win32 box).

main.c

@@ -36,6 +36,12 @@
 #include "findnonce.h"
 #include "ocl.h"
 
+#if defined(__linux)
+	#include <sys/mman.h>
+	#include <sys/wait.h>
+	#include <sys/types.h>
+#endif
+
 #define PROGRAM_NAME		"cgminer"
 #define DEF_RPC_URL		"http://127.0.0.1:8332/"
 #define DEF_RPC_USERNAME	"rpcuser"
@@ -118,6 +124,8 @@ struct strategies {
 	{ "Load Balance" },
 };
 
+static size_t max_name_len = 0;
+static char *name_spaces_pad = NULL;
 static const char *algo_names[] = {
 	[ALGO_C]		= "c",
 #ifdef WANT_SSE2_4WAY
@@ -138,6 +146,27 @@ static const char *algo_names[] = {
 #endif
 };
 
+typedef void (*sha256_func)();
+static const sha256_func sha256_funcs[] = {
+	[ALGO_C]		= (sha256_func)scanhash_c,
+#ifdef WANT_SSE2_4WAY
+	[ALGO_4WAY]		= (sha256_func)ScanHash_4WaySSE2,
+#endif
+#ifdef WANT_VIA_PADLOCK
+	[ALGO_VIA]		= (sha256_func)scanhash_via,
+#endif
+	[ALGO_CRYPTOPP]		=  (sha256_func)scanhash_cryptopp,
+#ifdef WANT_CRYPTOPP_ASM32
+	[ALGO_CRYPTOPP_ASM32]	= (sha256_func)scanhash_asm32,
+#endif
+#ifdef WANT_X8664_SSE2
+	[ALGO_SSE2_64]		= (sha256_func)scanhash_sse2_64,
+#endif
+#ifdef WANT_X8664_SSE4
+	[ALGO_SSE4_64]		= (sha256_func)scanhash_sse4_64
+#endif
+};
+
 bool opt_debug = false;
 bool opt_protocol = false;
 bool want_longpoll = true;
@@ -329,11 +358,268 @@ static struct pool *current_pool(void)
 	return pool;
 }
 
+static double bench_algo_stage3(
+	enum sha256_algos algo
+)
+{
+	static uint8_t some_block[] = {
+		0x00, 0x00, 0x00, 0x01, 0x20, 0x00, 0xD8, 0x07, 0x17, 0xC9, 0x13, 0x6F, 0xDC, 0xBE, 0xDE, 0xB7,
+		0xB2, 0x14, 0xEF, 0xD1, 0x72, 0x7F, 0xA3, 0x72, 0xB2, 0x5D, 0x88, 0xF0, 0x00, 0x00, 0x05, 0xAA,
+		0x00, 0x00, 0x00, 0x00, 0x92, 0x8B, 0x4C, 0x77, 0xF5, 0xB2, 0xE6, 0x56, 0x96, 0x27, 0xE0, 0x66,
+		0x3C, 0x5B, 0xDD, 0xDC, 0x88, 0x6A, 0x7D, 0x7C, 0x7B, 0x8C, 0xE4, 0x92, 0x38, 0x92, 0x58, 0x2E,
+		0x18, 0x4D, 0x95, 0x9E, 0x4E, 0x44, 0xF1, 0x5F, 0x1A, 0x08, 0xE1, 0xE5, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x02, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00,
+		0x86, 0x7E, 0x3A, 0xAF, 0x37, 0x83, 0xAF, 0xA0, 0xB5, 0x33, 0x2C, 0x28, 0xED, 0xA9, 0x89, 0x3E,
+		0x0A, 0xB6, 0x46, 0x81, 0xC2, 0x71, 0x4F, 0x34, 0x5A, 0x74, 0x89, 0x0E, 0x2B, 0x04, 0xB3, 0x16,
+		0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+		0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xA0, 0xF6, 0x09, 0x02, 0x00, 0x00, 0x00, 0x00,
+		0x55, 0xF1, 0x44, 0x4E, 0x00, 0x00, 0x00, 0x00, 0x79, 0x63, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	};
+	struct work work __attribute__((aligned(128)));
+	assert(sizeof(work) == sizeof(some_block));
+	memcpy(&work, &some_block, sizeof(work));
+
+	struct work_restart dummy;
+	work_restart = &dummy;
+
+	struct timeval end;
+	struct timeval start;
+	uint64_t hashes_done = 0;
+	uint32_t max_nonce = (1<<21);
+
+	gettimeofday(&start, 0);
+		#ifdef WANT_VIA_PADLOCK
+			if (ALGO_VIA==algo) {
+				(void)scanhash_via(
+					0,
+					work.data,
+					work.target,
+					max_nonce,
+					&hashes_done,
+					work.blk.nonce
+				);
+			} else
+		#endif
+		{
+			sha256_func func = sha256_funcs[algo];
+			(*func)(
+				0,
+				work.midstate,
+				work.data + 64,
+				work.hash1,
+				work.hash,
+				work.target,
+				max_nonce,
+				&hashes_done,
+				work.blk.nonce
+			);
+		}
+	gettimeofday(&end, 0);
+	work_restart = NULL;
+
+	uint64_t usec_end = ((uint64_t)end.tv_sec)*1000*1000 + end.tv_usec;
+	uint64_t usec_start = ((uint64_t)start.tv_sec)*1000*1000 + start.tv_usec;
+	uint64_t usec_elapsed = usec_end - usec_start;
+
+	double rate = -1.0;
+	if (0<usec_elapsed) {
+		rate = (1.0*hashes_done)/usec_elapsed;
+	}
+	return rate;
+}
+
+static double bench_algo_stage2(
+	enum sha256_algos algo
+)
+{
+	#if defined(__linux)
+		// Make a shared+anonymous mmap
+		const size_t map_size = 4096;
+		void *map = mmap(
+			(void*)NULL,
+			map_size,
+			PROT_READ |
+			PROT_WRITE,
+			MAP_SHARED   |
+			MAP_ANONYMOUS,
+			-1,
+			0
+		);
+		if ((void*)-1 == map) {
+			perror("bench algo, mmap failed");
+			exit(1);
+		}
+
+		// Load a canary rate in the map
+		double rate = -1.23457;
+		memcpy(map, &rate, sizeof(rate));
+
+		// Fork a child to do the actual benchmarking
+		pid_t child_pid = fork();
+		if (0==child_pid) {
+
+			// Do the dangerous work in the child
+			double r = bench_algo_stage3(algo);
+
+			// Load result in shared map and bail
+			memcpy(map, &r, sizeof(r));
+			exit(0);
+		}
+
+		// Parent waits for a result from child
+		int nb_loops = 0;
+		while (1) {
+
+			// Wait for child to die
+			int status;
+			int r = waitpid(child_pid, &status, WNOHANG);
+			if (child_pid==r) {
+				// Child died somehow. Copy result and bail
+				memcpy(&rate, map, sizeof(rate));
+				break;
+			} else if (r<0) {
+				perror("bench_algo: waitpid failed. giving up.");
+				exit(1);
+			}
+
+			// Give up on child after a ~60s
+			if (60<nb_loops) {
+				kill(child_pid, SIGKILL);
+				waitpid(child_pid, &status, 0);
+				break;
+			}
+
+			// Wait a bit longer
+			++nb_loops;
+			sleep(1);
+		}
+
+		// Clean up shared map
+		int r = munmap(map, map_size);
+		if (r<0) {
+			perror("bench algo, munmap failed");
+			exit(1);
+		}
+	#else
+		// Not on linux, just run the risk of an illegal instruction
+		rate = bench_algo_stage3(algo);
+	#endif
+
+	// Done
+	return rate;
+}
+
+static void bench_algo(
+	double            *best_rate,
+	enum sha256_algos *best_algo,
+	enum sha256_algos algo
+)
+{
+	size_t n = max_name_len - strlen(algo_names[algo]);
+	memset(name_spaces_pad, ' ', n);
+	name_spaces_pad[n] = 0;
+
+	applog(LOG_ERR, "\"%s\"%s : benchmarking algorithm ...", algo_names[algo], name_spaces_pad);
+	double rate = bench_algo_stage2(algo);
+
+	if (rate<0.0) {
+		applog(LOG_ERR, "\"%s\"%s : algorithm fails on this platform", algo_names[algo], name_spaces_pad);
+	} else {
+		applog(LOG_ERR, "\"%s\"%s : algorithm runs at %.5f MH/s", algo_names[algo], name_spaces_pad, rate);
+		if (*best_rate<rate) {
+			*best_rate = rate;
+			*best_algo = algo;
+		}
+	}
+}
+
+static void init_max_name_len()
+{
+	size_t i;
+	size_t nb_names = sizeof(algo_names)/sizeof(algo_names[0]);
+	for (i=0; i<nb_names; ++i) {
+		const char *p = algo_names[i];
+		size_t name_len = p ? strlen(p) : 0;
+		if (max_name_len<name_len) {
+			max_name_len = name_len;
+		}
+	}
+
+	name_spaces_pad = (char*) malloc(max_name_len+16);
+	if (0==name_spaces_pad) {
+		perror("malloc failed");
+		exit(1);
+	}
+}
+
+static enum sha256_algos pick_fastest_algo()
+{
+	double best_rate = -1.0;
+	enum sha256_algos best_algo = 0;
+
+	bench_algo(&best_rate, &best_algo, ALGO_C);
+	#ifdef WANT_SSE2_4WAY
+		bench_algo(&best_rate, &best_algo, ALGO_4WAY);
+	#endif
+	#ifdef WANT_VIA_PADLOCK
+		bench_algo(&best_rate, &best_algo, ALGO_VIA);
+	#endif
+	bench_algo(&best_rate, &best_algo, ALGO_CRYPTOPP);
+	#ifdef WANT_CRYPTOPP_ASM32
+		bench_algo(&best_rate, &best_algo, ALGO_CRYPTOPP_ASM32);
+	#endif
+	#ifdef WANT_X8664_SSE2
+		bench_algo(&best_rate, &best_algo, ALGO_SSE2_64);
+	#endif
+	#ifdef WANT_X8664_SSE4
+		bench_algo(&best_rate, &best_algo, ALGO_SSE4_64);
+	#endif
+
+	size_t n = max_name_len - strlen(algo_names[best_algo]);
+	memset(name_spaces_pad, ' ', n);
+	name_spaces_pad[n] = 0;
+	applog(
+		LOG_ERR,
+		"\"%s\"%s : is fastest algorithm at %.5f MH/s",
+		algo_names[best_algo],
+		name_spaces_pad,
+		best_rate
+	);
+
+	return best_algo;
+}
+
 /* FIXME: Use asprintf for better errors. */
 static char *set_algo(const char *arg, enum sha256_algos *algo)
 {
 	enum sha256_algos i;
 
+	if (!strcmp(arg, "auto")) {
+		*algo = pick_fastest_algo();
+		return NULL;
+	}
+
 	for (i = 0; i < ARRAY_SIZE(algo_names); i++) {
 		if (algo_names[i] && !strcmp(arg, algo_names[i])) {
 			*algo = i;
@@ -515,7 +801,8 @@ static struct opt_table opt_config_table[] = {
 	OPT_WITH_ARG("--algo|-a",
 		     set_algo, show_algo, &opt_algo,
 		     "Specify sha256 implementation for CPU mining:\n"
-		     "\tc\t\tLinux kernel sha256, implemented in C"
+		     "\tauto\t\tBenchmark at startup and pick fastest algorithm"
+		     "\n\tc\t\tLinux kernel sha256, implemented in C"
 #ifdef WANT_SSE2_4WAY
 		     "\n\t4way\t\ttcatm's 4-way SSE2 implementation"
 #endif
@@ -809,7 +1096,7 @@ static void curses_print_status(int thr_id)
 
 	wmove(statuswin, 0, 0);
 	wattron(statuswin, A_BOLD);
-	wprintw(statuswin, " " PROGRAM_NAME " version " VERSION " - Started: %s", datestamp);
+	wprintw(statuswin, " " PROGRAM_NAME " version " VERSION " - Started: %s CPU Algo: %s", datestamp, algo_names[opt_algo]);
 	wattroff(statuswin, A_BOLD);
 	wmove(statuswin, 1, 0);
 	whline(statuswin, '-', 80);
@@ -3862,6 +4149,8 @@ int main (int argc, char *argv[])
 	if (unlikely(pthread_mutex_init(&control_lock, NULL)))
 		quit(1, "Failed to pthread_mutex_init");
 
+	init_max_name_len();
+
 	handler.sa_handler = &sighandler;
 	sigaction(SIGTERM, &handler, &termhandler);
 	sigaction(SIGINT, &handler, &inthandler);