oom-trigger.c

#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#define ONE_MB            (1024 * 1024)
#define SLEEP_BUF_DEFAULT 16            // wait 1s every N MB
#define SLEEP_BUF_MIN     0
#define SLEEP_BUF_MAX     (1024 * 1024) // surely nobody has 1 TB lying around
#define SLEEP_ITER_ENV    "SLEEP_ITER"

int main(int argc, char* argv[]) {
	const int page_sz = getpagesize();
	printf("page_sz=%d\n", page_sz);
	assert(page_sz > 0);

	// page size is going to be either 4K or 16K
	const int per_mb = ONE_MB / page_sz;
	printf("per_mb=%d\n", per_mb);
	assert(per_mb > 0);

	char *pTmp;
	int sleep_buf;
	if (( pTmp = getenv( "SLEEP_ITER" )) != NULL ) {
		sleep_buf = atoi(pTmp);
	} else {
		sleep_buf = SLEEP_BUF_DEFAULT;
	}
	sleep_buf = sleep_buf < SLEEP_BUF_MIN ? SLEEP_BUF_MIN : (sleep_buf > SLEEP_BUF_MAX ? SLEEP_BUF_MAX : sleep_buf);

	size_t mb_count = 0;
	char *block;
	while (1) {
		block = (char*) calloc(1, ONE_MB);
		mb_count++;
		printf("alloc: %zu MB\n", mb_count);
		for (int page = 0; page < per_mb; page++) {
			block[page*page_sz] = (page % 2) ? 'A' : '!';
		}
		printf("touch: %zu MB\n", mb_count);
		if (sleep_buf && mb_count % sleep_buf == 0) {
			sleep(1);
		}
	}
}