sets.c   [plain text]

#include <AvailabilityMacros.h>
#include <mach/thread_policy.h>
#include <mach/mach.h>
#include <mach/mach_error.h>
#include <mach/mach_time.h>
#include <pthread.h>
#include <sys/queue.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <err.h>
#include <errno.h>
#include <sys/sysctl.h>

/*
 * Sets is a multithreaded test/benchmarking program to evaluate
 * affinity set placement in Leopard.
 *
 * The picture here, for each set, is:
 *
 *       free                   work
 *    -> queue --> producer --> queue --> consumer --
 *   |                                               |
 *    -----------------------------------------------
 *
 *       <------ "stage" -----> <------ "stage" ----->
 *
 * We spin off sets of production line threads (2 sets by default).
 * All threads of each line sets the same affinity tag (unless disabled).
 * By default there are 2 stage (worker) threads per production line.
 * A worker thread removes a buffer from an input queue, processses it and
 * queues it on an output queue.  By default the initial stage (producer)
 * writes every byte in a buffer and the other (consumer) stages read every
 * byte. By default the buffers are 1MB (256 pages) in size but this can be
 * overidden.  By default there are 2 buffers per set (again overridable).
 * Worker threads process (iterate over) 10000 buffers by default.
 *
 * With affinity enabled, each producer and consumer thread sets its affinity
 * to the set number, 1 .. N. So the threads of each set share an L2 cache.
 *
 * Buffer management uses pthread mutex/condition variables. A thread blocks
 * when no buffer is available on a queue and it is signaled when a buffer
 * is placed on an empty queue. Queues are tailq'a a la <sys/queue.h>.
 * The queue management is centralized in a single routine: what queues to
 * use as input and output and what function to call for processing is
 * data-driven.
 */

pthread_mutex_t funnel;
pthread_cond_t  barrier;

uint64_t        timer;
int             threads;
int             threads_ready = 0;

int             iterations = 10000;
boolean_t       affinity = FALSE;
boolean_t       halting = FALSE;
boolean_t       cache_config = FALSE;
int             verbosity = 1;

typedef struct work {
	TAILQ_ENTRY(work)       link;
	int                     *data;
} work_t;

/*
 * A work queue, complete with pthread objects for its management
 */
typedef struct work_queue {
	pthread_mutex_t         mtx;
	pthread_cond_t          cnd;
	TAILQ_HEAD(, work)      queue;
	boolean_t               waiters;
} work_queue_t;

/* Worker functions take a integer array and size */
typedef void (worker_fn_t)(int *, int);

/* This struct controls the function of a thread */
typedef struct {
	int                     stagenum;
	char                    *name;
	worker_fn_t             *fn;
	work_queue_t            *input;
	work_queue_t            *output;
	struct line_info        *set;
	pthread_t               thread;
	work_queue_t            bufq;
} stage_info_t;

/* This defines a thread set */
#define WORKERS_MAX 10
typedef struct line_info {
	int                     setnum;
	int                     *data;
	int                     isize;
	stage_info_t            *stage[WORKERS_MAX];
} line_info_t;

#define DBG(x...) do {                          \
	if (verbosity > 1) {                    \
	        pthread_mutex_lock(&funnel);    \
	        printf(x);                      \
	        pthread_mutex_unlock(&funnel);  \
	}                                       \
} while (0)

#define mutter(x...) do {                       \
	if (verbosity > 0) {                    \
	        printf(x);                      \
	}                                       \
} while (0)

#define s_if_plural(x)  (((x) > 1) ? "s" : "")

static void
usage()
{
	fprintf(stderr,
	    "usage: sets [-a]   Turn affinity on (off)\n"
	    "            [-b B] Number of buffers per set/line (2)\n"
	    "            [-c]   Configure for max cache performance\n"
	    "            [-h]   Print this\n"
	    "            [-i I] Number of items/buffers to process (1000)\n"
	    "            [-s S] Number of stages per set/line (2)\n"
	    "            [-t]   Halt for keyboard input to start\n"
	    "            [-p P] Number of pages per buffer (256=1MB)]\n"
	    "            [-w]   Consumer writes data\n"
	    "            [-v V] Level of verbosity 0..2 (1)\n"
	    "            [N]    Number of sets/lines (2)\n"
	    );
	exit(1);
}

/* Trivial producer: write to each byte */
void
writer_fn(int *data, int isize)
{
	int     i;

	for (i = 0; i < isize; i++) {
		data[i] = i;
	}
}

/* Trivial consumer: read each byte */
void
reader_fn(int *data, int isize)
{
	int     i;
	int     datum;

	for (i = 0; i < isize; i++) {
		datum = data[i];
	}
}

/* Consumer reading and writing the buffer */
void
reader_writer_fn(int *data, int isize)
{
	int     i;

	for (i = 0; i < isize; i++) {
		data[i] += 1;
	}
}

/*
 * This is the central function for every thread.
 * For each invocation, its role is ets by (a pointer to) a stage_info_t.
 */
void *
manager_fn(void *arg)
{
	stage_info_t                    *sp = (stage_info_t *) arg;
	line_info_t                     *lp = sp->set;
	kern_return_t                   ret;
	long                            iteration = 0;

	/*
	 * If we're using affinity sets (we are by default)
	 * set our tag to by our thread set number.
	 */
	thread_extended_policy_data_t   epolicy;
	thread_affinity_policy_data_t   policy;

	epolicy.timeshare = FALSE;
	ret = thread_policy_set(
		mach_thread_self(), THREAD_EXTENDED_POLICY,
		(thread_policy_t) &epolicy,
		THREAD_EXTENDED_POLICY_COUNT);
	if (ret != KERN_SUCCESS) {
		printf("thread_policy_set(THREAD_EXTENDED_POLICY) returned %d\n", ret);
	}

	if (affinity) {
		policy.affinity_tag = lp->setnum;
		ret = thread_policy_set(
			mach_thread_self(), THREAD_AFFINITY_POLICY,
			(thread_policy_t) &policy,
			THREAD_AFFINITY_POLICY_COUNT);
		if (ret != KERN_SUCCESS) {
			printf("thread_policy_set(THREAD_AFFINITY_POLICY) returned %d\n", ret);
		}
	}

	DBG("Starting %s set: %d stage: %d\n", sp->name, lp->setnum, sp->stagenum);

	/*
	 * Start barrier.
	 * The tets thread to get here releases everyone and starts the timer.
	 */
	pthread_mutex_lock(&funnel);
	threads_ready++;
	if (threads_ready == threads) {
		pthread_mutex_unlock(&funnel);
		if (halting) {
			printf("  all threads ready for process %d, "
			    "hit any key to start", getpid());
			fflush(stdout);
			(void) getchar();
		}
		pthread_cond_broadcast(&barrier);
		timer = mach_absolute_time();
	} else {
		pthread_cond_wait(&barrier, &funnel);
		pthread_mutex_unlock(&funnel);
	}

	do {
		int             i;
		work_t          *workp;

		/*
		 * Get a buffer from the input queue.
		 * Block if none.
		 */
		pthread_mutex_lock(&sp->input->mtx);
		while (1) {
			workp = TAILQ_FIRST(&(sp->input->queue));
			if (workp != NULL) {
				break;
			}
			DBG("    %s[%d,%d] iteration %d waiting for buffer\n",
			    sp->name, lp->setnum, sp->stagenum, iteration);
			sp->input->waiters = TRUE;
			pthread_cond_wait(&sp->input->cnd, &sp->input->mtx);
			sp->input->waiters = FALSE;
		}
		TAILQ_REMOVE(&(sp->input->queue), workp, link);
		pthread_mutex_unlock(&sp->input->mtx);

		DBG("  %s[%d,%d] iteration %d work %p data %p\n",
		    sp->name, lp->setnum, sp->stagenum, iteration, workp, workp->data);

		/* Do our stuff with the buffer */
		(void) sp->fn(workp->data, lp->isize);

		/*
		 * Place the buffer on the input queue.
		 * Signal  waiters if required.
		 */
		pthread_mutex_lock(&sp->output->mtx);
		TAILQ_INSERT_TAIL(&(sp->output->queue), workp, link);
		if (sp->output->waiters) {
			DBG("    %s[%d,%d] iteration %d signaling work\n",
			    sp->name, lp->setnum, sp->stagenum, iteration);
			pthread_cond_signal(&sp->output->cnd);
		}
		pthread_mutex_unlock(&sp->output->mtx);
	} while (++iteration < iterations);

	DBG("Ending %s[%d,%d]\n", sp->name, lp->setnum, sp->stagenum);

	return (void *) iteration;
}

#define MAX_CACHE_DEPTH 10
static void
auto_config(int npages, int *nbufs, int *nsets)
{
	size_t  len;
	int     ncpu;
	int     llc;
	int64_t cacheconfig[MAX_CACHE_DEPTH];
	int64_t cachesize[MAX_CACHE_DEPTH];

	mutter("Autoconfiguring...\n");

	len = sizeof(cacheconfig);
	if (sysctlbyname("hw.cacheconfig",
	    &cacheconfig[0], &len, NULL, 0) != 0) {
		printf("Unable to get hw.cacheconfig, %d\n", errno);
		exit(1);
	}
	len = sizeof(cachesize);
	if (sysctlbyname("hw.cachesize",
	    &cachesize[0], &len, NULL, 0) != 0) {
		printf("Unable to get hw.cachesize, %d\n", errno);
		exit(1);
	}

	/*
	 * Find LLC
	 */
	for (llc = MAX_CACHE_DEPTH - 1; llc > 0; llc--) {
		if (cacheconfig[llc] != 0) {
			break;
		}
	}

	/*
	 * Calculate number of buffers of size pages*4096 bytes
	 * fit into 90% of an L2 cache.
	 */
	*nbufs = cachesize[llc] * 9 / (npages * 4096 * 10);
	mutter("  L%d (LLC) cache %qd bytes: "
	    "using %d buffers of size %d bytes\n",
	    llc, cachesize[llc], *nbufs, (npages * 4096));

	/*
	 * Calcalute how many sets:
	 */
	*nsets = cacheconfig[0] / cacheconfig[llc];
	mutter("  %qd cpus; %qd cpus per L%d cache: using %d sets\n",
	    cacheconfig[0], cacheconfig[llc], llc, *nsets);
}

void (*producer_fnp)(int *data, int isize) = &writer_fn;
void (*consumer_fnp)(int *data, int isize) = &reader_fn;

int
main(int argc, char *argv[])
{
	int                     i;
	int                     j;
	int                     pages = 256; /* 1MB */
	int                     buffers = 2;
	int                     sets = 2;
	int                     stages = 2;
	int                     *status;
	line_info_t             *line_info;
	line_info_t             *lp;
	stage_info_t            *stage_info;
	stage_info_t            *sp;
	kern_return_t           ret;
	int                     c;

	/* Do switch parsing: */
	while ((c = getopt(argc, argv, "ab:chi:p:s:twv:")) != -1) {
		switch (c) {
		case 'a':
			affinity = !affinity;
			break;
		case 'b':
			buffers = atoi(optarg);
			break;
		case 'c':
			cache_config = TRUE;
			break;
		case 'i':
			iterations = atoi(optarg);
			break;
		case 'p':
			pages = atoi(optarg);
			break;
		case 's':
			stages = atoi(optarg);
			if (stages >= WORKERS_MAX) {
				usage();
			}
			break;
		case 't':
			halting = TRUE;
			break;
		case 'w':
			consumer_fnp = &reader_writer_fn;
			break;
		case 'v':
			verbosity = atoi(optarg);
			break;
		case '?':
		case 'h':
		default:
			usage();
		}
	}
	argc -= optind; argv += optind;
	if (argc > 0) {
		sets = atoi(*argv);
	}

	if (cache_config) {
		auto_config(pages, &buffers, &sets);
	}

	pthread_mutex_init(&funnel, NULL);
	pthread_cond_init(&barrier, NULL);

	/*
	 * Fire up the worker threads.
	 */
	threads = sets * stages;
	mutter("Launching %d set%s of %d threads with %saffinity, "
	    "consumer reads%s data\n",
	    sets, s_if_plural(sets), stages, affinity? "": "no ",
	    (consumer_fnp == &reader_writer_fn)? " and writes" : "");
	if (pages < 256) {
		mutter("  %dkB bytes per buffer, ", pages * 4);
	} else {
		mutter("  %dMB bytes per buffer, ", pages / 256);
	}
	mutter("%d buffer%s per set ",
	    buffers, s_if_plural(buffers));
	if (buffers * pages < 256) {
		mutter("(total %dkB)\n", buffers * pages * 4);
	} else {
		mutter("(total %dMB)\n", buffers * pages / 256);
	}
	mutter("  processing %d buffer%s...\n",
	    iterations, s_if_plural(iterations));
	line_info = (line_info_t *) malloc(sets * sizeof(line_info_t));
	stage_info = (stage_info_t *) malloc(sets * stages * sizeof(stage_info_t));
	for (i = 0; i < sets; i++) {
		work_t  *work_array;

		lp = &line_info[i];

		lp->setnum = i + 1;
		lp->isize = pages * 4096 / sizeof(int);
		lp->data = (int *) malloc(buffers * pages * 4096);

		/* Set up the queue for the workers of this thread set: */
		for (j = 0; j < stages; j++) {
			sp = &stage_info[(i * stages) + j];
			sp->stagenum = j;
			sp->set = lp;
			lp->stage[j] = sp;
			pthread_mutex_init(&sp->bufq.mtx, NULL);
			pthread_cond_init(&sp->bufq.cnd, NULL);
			TAILQ_INIT(&sp->bufq.queue);
			sp->bufq.waiters = FALSE;
		}

		/*
		 * Take a second pass through the stages
		 * to define what the workers are and to interconnect their input/outputs
		 */
		for (j = 0; j < stages; j++) {
			sp = lp->stage[j];
			if (j == 0) {
				sp->fn = producer_fnp;
				sp->name = "producer";
			} else {
				sp->fn = consumer_fnp;
				sp->name = "consumer";
			}
			sp->input = &lp->stage[j]->bufq;
			sp->output = &lp->stage[(j + 1) % stages]->bufq;
		}

		/* Set up the buffers on the first worker of the set. */
		work_array = (work_t *)  malloc(buffers * sizeof(work_t));
		for (j = 0; j < buffers; j++) {
			work_array[j].data = lp->data + (lp->isize * j);
			TAILQ_INSERT_TAIL(&lp->stage[0]->bufq.queue, &work_array[j], link);
			DBG("  empty work item %p for set %d data %p\n",
			    &work_array[j], i, work_array[j].data);
		}

		/* Create this set of threads */
		for (j = 0; j < stages; j++) {
			if (ret = pthread_create(&lp->stage[j]->thread, NULL,
			    &manager_fn,
			    (void *) lp->stage[j])) {
				err(1, "pthread_create %d,%d", i, j);
			}
		}
	}

	/*
	 * We sit back anf wait for the slave to finish.
	 */
	for (i = 0; i < sets; i++) {
		lp = &line_info[i];
		for (j = 0; j < stages; j++) {
			if (ret = pthread_join(lp->stage[j]->thread, (void **)&status)) {
				err(1, "pthread_join %d,%d", i, j);
			}
			DBG("Thread %d,%d status %d\n", i, j, status);
		}
	}

	/*
	 * See how long the work took.
	 */
	timer = mach_absolute_time() - timer;
	timer = timer / 1000000ULL;
	printf("%d.%03d seconds elapsed.\n",
	    (int) (timer / 1000ULL), (int) (timer % 1000ULL));

	return 0;
}