resctrl_cache_alloc.c

gistfile1.txt

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <sys/stat.h>
#include <regex.h>

#define MAX_BUFFER_SIZE 512

int main(int argc, char *argv[]) {
	char rest[MAX_BUFFER_SIZE]={0};
	char format[MAX_BUFFER_SIZE];
	char buffer[MAX_BUFFER_SIZE];
	char hex[MAX_BUFFER_SIZE];
	unsigned long mask = 1;
	regmatch_t pmatch[3];
	unsigned long number;
	unsigned long num;
	int count = 0;
	regex_t regex;
	char *errc;
	FILE *file;
	FILE *out;
	int reti;
	int pid;

	if (argc != 2) {
		printf("Usage: %s <pid>\n", argv[0]);
		return -1;
	}

	pid = strtol(argv[1], &errc, 10);
	if (pid ==0) {
		perror("Pid is supposed to be a number\n");
		return -1;
	}

	if (kill(pid, 0) == -1) {
		perror("Pid not running");
		return -1;
	}

	file = fopen("/sys/fs/resctrl/schemata", "r");
	if (file == NULL) {
		perror("Failed to access /sys/fs/resctrl/schemata\n is resctrl filesystem mounted?\n try: mount -t resctrl resctrl /sys/fs/resctrl");
		return -1;
	}

	while (fgets(buffer, sizeof(buffer), file)) {
		reti = regcomp(&regex, "L3:[0-9]+=([0-9a-f]+)(.*)\n", REG_EXTENDED);
		if (reti) {
			fprintf(stderr, "Could not compile regex\n");
			return -1;
		}

		reti = regexec(&regex, buffer, 3, pmatch, 0);
		if (!reti) {
			memcpy(hex, buffer + pmatch[1].rm_so, pmatch[1].rm_eo - pmatch[1].rm_so);
			printf("0 start=%d, len=%d\n", pmatch[0].rm_so, pmatch[0].rm_eo);
			printf("1 start=%d, len=%d\n", pmatch[1].rm_so, pmatch[1].rm_eo);
			printf("2 start=%d, len=%d\n", pmatch[2].rm_so, pmatch[2].rm_eo);

			memcpy(rest, buffer + pmatch[2].rm_so, pmatch[2].rm_eo - pmatch[2].rm_so);
			printf("but=%s, the rest='%s'\n", buffer, rest);
			hex[pmatch[1].rm_eo - pmatch[1].rm_so] = '\0';
			num = strtoul(hex, NULL, 16);

			while (mask !=0 ) {
				if (num & mask) count++;
				mask <<= 1;
			}
			number = (1UL << (count / 2)) - 1;
			printf("%d\n", snprintf(format, sizeof(format), "L3:0=%%0%dlx%%s\n", count / 4));
			printf("%s\n", format);
			printf("restricting PID %d to socket0 and allocate 50%% of the cache to it\n", pid);
			mkdir("/sys/fs/resctrl/1", 0666);
			out =  fopen("/sys/fs/resctrl/schemata", "w+");
			fprintf(out, format, num - number, rest);
			fclose(out);
			out =  fopen("/sys/fs/resctrl/1/schemata", "w+");
			fprintf(out, format, number, rest);
			fclose(out);
			out =  fopen("/sys/fs/resctrl/1/tasks", "w+");
			fprintf(out, "%d\n", pid);
			fclose(out);

			regfree(&regex);
			fclose(file);
			return 0;
		}
		regfree(&regex);
	}

	printf("No matching line found in schemata\n");
	fclose(file);
	return -1;
}