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/* Start/stop KSM, for systemd.
* Copyright (C) 2009, 2011 Red Hat, Inc.
* Written by Paolo Bonzini <pbonzini@redhat.com>.
* Based on the original sysvinit script by Dan Kenigsberg <danken@redhat.com>
* This file is distributed under the GNU General Public License, version 2
* or later. */
#include <unistd.h>
#include <stdio.h>
#include <limits.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#define KSM_MAX_KERNEL_PAGES_FILE "/sys/kernel/mm/ksm/max_kernel_pages"
#define KSM_RUN_FILE "/sys/kernel/mm/ksm/run"
char *program_name;
int usage(void)
{
fprintf(stderr, "Usage: %s {start|stop}\n", program_name);
return 1;
}
int write_value(uint64_t value, char *filename)
{
FILE *fp;
if (!(fp = fopen(filename, "w")) ||
fprintf(fp, "%llu\n", (unsigned long long) value) == EOF ||
fflush(fp) == EOF ||
fclose(fp) == EOF)
return 1;
return 0;
}
uint64_t ksm_max_kernel_pages()
{
char *var = getenv("KSM_MAX_KERNEL_PAGES");
char *endptr;
uint64_t value;
if (var && *var) {
value = strtoll(var, &endptr, 0);
if (value < LLONG_MAX && !*endptr)
return value;
}
/* Unless KSM_MAX_KERNEL_PAGES is set, let KSM munch up to half of
* total memory. */
return sysconf(_SC_PHYS_PAGES) / 2;
}
int start(void)
{
if (access(KSM_MAX_KERNEL_PAGES_FILE, R_OK) >= 0)
write_value(ksm_max_kernel_pages(), KSM_MAX_KERNEL_PAGES_FILE);
return write_value(1, KSM_RUN_FILE);
}
int stop(void)
{
return write_value(0, KSM_RUN_FILE);
}
int main(int argc, char **argv)
{
program_name = argv[0];
if (argc < 2) {
return usage();
} else if (!strcmp(argv[1], "start")) {
return start();
} else if (!strcmp(argv[1], "stop")) {
return stop();
} else {
return usage();
}
}
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