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