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/*
* cpuplugd - Linux for System z Hotplug Daemon
*
* cmm functions
*
* Copyright IBM Corp. 2007, 2017
*
* s390-tools is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
#include "cpuplugd.h"
/*
* The cmm_pages value defines the size of the balloon of blocked memory.
* Increasing the value is removing memory from Linux, which is an memunplug.
* Decreasing the value is adding memory back to Linux, which is memplug.
*/
/*
* Set the value of cmm_pages
*/
void set_cmm_pages(long pages)
{
FILE *filp;
filp = fopen("/proc/sys/vm/cmm_pages", "w");
if (!filp)
cpuplugd_exit("Cannot open /proc/sys/vm/cmmpages: %s\n",
strerror(errno));
cpuplugd_debug("changing number of pages permanently reserved to %ld\n",
pages);
fprintf(filp, "%ld\n", pages);
fclose(filp);
return;
}
/*
* Read number of pages permanently reserved
*/
long get_cmmpages_size()
{
FILE *filp;
long size;
int rc;
filp = fopen("/proc/sys/vm/cmm_pages", "r");
if (!filp)
cpuplugd_exit("Cannot open /proc/sys/vm/cmm_pages: %s\n",
strerror(errno));
rc = fscanf(filp, "%ld", &size);
if (rc == 0)
cpuplugd_exit("Can not read /proc/sys/vm/cmm_pages: %s\n",
strerror(errno));
fclose(filp);
return size;
}
/*
* Reset cmm pagesize to value we found prior to daemon startup
*/
void cleanup_cmm()
{
set_cmm_pages(cmm_pagesize_start);
return;
}
/*
* Function to check if the cmm kernel module is loaded and the required
* files below /proc exit
*/
int check_cmmfiles(void)
{
FILE *filp;
filp = fopen("/proc/sys/vm/cmm_pages", "r");
if (!filp)
return -1;
fclose(filp);
return 0;
}
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