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/*
* elvtune.c - I/O elevator tuner
*
* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
* This file may be redistributed under the terms of the GNU General
* Public License, version 2.
*/
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <getopt.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include "nls.h"
/* this has to match with the kernel structure */
/* current version for ac19 and 2.2.16 */
typedef struct blkelv_ioctl_arg_s {
int queue_ID;
int read_latency;
int write_latency;
int max_bomb_segments;
} blkelv_ioctl_arg_t;
/* ioctls introduced in 2.2.16, removed in 2.5.58 */
#define BLKELVGET _IOR(0x12,106,size_t)
#define BLKELVSET _IOW(0x12,107,size_t)
static void
usage(void) {
fprintf(stderr, "elvtune (%s)\n", PACKAGE_STRING);
fprintf(stderr, _("usage:\n"));
fprintf(stderr, "\telvtune [-r r_lat] [-w w_lat] [-b b_lat]"
" /dev/blkdev1 [/dev/blkdev2...]\n");
fprintf(stderr, "\telvtune -h\n");
fprintf(stderr, "\telvtune -v\n");
fprintf(stderr, "\tNOTE: elvtune only works with 2.4 kernels\n");
/* (ioctls exist in 2.2.16 - 2.5.57) */
}
static void
version(void) {
fprintf(stderr, "elvtune (%s)\n", PACKAGE_STRING);
}
#define MAKE_VERSION(p,q,r) (65536*(p) + 256*(q) + (r))
static int
linux_version_code(void) {
struct utsname my_utsname;
int p, q, r;
if (uname(&my_utsname) == 0) {
p = atoi(strtok(my_utsname.release, "."));
q = atoi(strtok(NULL, "."));
r = atoi(strtok(NULL, "."));
return MAKE_VERSION(p,q,r);
}
return 0;
}
int
main(int argc, char * argv[]) {
int read_value = 0xbeefbeef, write_value = 0xbeefbeef, bomb_value = 0xbeefbeef;
int read_set, write_set, bomb_set, set;
char * devname;
int fd;
blkelv_ioctl_arg_t elevator;
read_set = write_set = bomb_set = set = 0;
for (;;) {
int opt;
opt = getopt(argc, argv, "r:w:b:hv");
if (opt == -1)
break;
switch (opt) {
case 'r':
read_value = atoi(optarg);
read_set = set = 1;
break;
case 'w':
write_value = atoi(optarg);
write_set = set = 1;
break;
case 'b':
bomb_value = atoi(optarg);
bomb_set = set = 1;
break;
case 'h':
usage(), exit(0);
case 'v':
version(), exit(0);
case '?':
default:
case ':':
fprintf(stderr, "parse error\n");
exit(1);
}
}
if (optind >= argc)
fprintf(stderr, "missing blockdevice, use -h for help\n"), exit(1);
while (optind < argc) {
devname = argv[optind++];
fd = open(devname, O_RDONLY|O_NONBLOCK);
if (fd < 0) {
perror("open");
break;
}
/* mmj: If we get EINVAL it's not a 2.4 kernel, so warn about
that and exit. It should return ENOTTY however, so check for
that as well in case it gets corrected in the future */
if (ioctl(fd, BLKELVGET, &elevator) < 0) {
int errsv = errno;
perror("ioctl get");
if ((errsv == EINVAL || errsv == ENOTTY) &&
linux_version_code() >= MAKE_VERSION(2,5,58)) {
fprintf(stderr,
"\nelvtune is only useful on older "
"kernels;\nfor 2.6 use IO scheduler "
"sysfs tunables instead..\n");
}
break;
}
if (set) {
if (read_set)
elevator.read_latency = read_value;
if (write_set)
elevator.write_latency = write_value;
if (bomb_set)
elevator.max_bomb_segments = bomb_value;
if (ioctl(fd, BLKELVSET, &elevator) < 0) {
perror("ioctl set");
break;
}
if (ioctl(fd, BLKELVGET, &elevator) < 0) {
perror("ioctl reget");
break;
}
}
printf("\n%s elevator ID\t\t%d\n", devname, elevator.queue_ID);
printf("\tread_latency:\t\t%d\n", elevator.read_latency);
printf("\twrite_latency:\t\t%d\n", elevator.write_latency);
printf("\tmax_bomb_segments:\t%d\n\n", elevator.max_bomb_segments);
if (close(fd) < 0) {
perror("close");
break;
}
}
return 0;
}
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