io/madvise.c

   1 /*
   2  * Copyright (c) 2004-2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18
  19 #include "xfs/xfs.h"
  20 #include "xfs/command.h"
  21 #include "xfs/input.h"
  22 #include <sys/mman.h>
  23 #include "init.h"
  24 #include "io.h"
  25
  26 static cmdinfo_t madvise_cmd;
  27
  28 static void
  29 madvise_help(void)
  30 {
  31         printf(_(
  32 "\n"
  33 " advise the page cache about access patterns expected for a mapping\n"
  34 "\n"
  35 " Modifies page cache behavior when operating on the current mapping.\n"
  36 " The range arguments are required by some advise commands ([*] below).\n"
  37 " With no arguments, the POSIX_MADV_NORMAL advice is implied.\n"
  38 " -d -- don't need these pages (POSIX_MADV_DONTNEED) [*]\n"
  39 " -r -- expect random page references (POSIX_MADV_RANDOM)\n"
  40 " -s -- expect sequential page references (POSIX_MADV_SEQUENTIAL)\n"
  41 " -w -- will need these pages (POSIX_MADV_WILLNEED) [*]\n"
  42 " Notes:\n"
  43 "   NORMAL sets the default readahead setting on the file.\n"
  44 "   RANDOM sets the readahead setting on the file to zero.\n"
  45 "   SEQUENTIAL sets double the default readahead setting on the file.\n"
  46 "   WILLNEED forces the maximum readahead.\n"
  47 "\n"));
  48 }
  49
  50 int
  51 madvise_f(
  52         int             argc,
  53         char            **argv)
  54 {
  55         off64_t         offset, llength;
  56         size_t          length;
  57         void            *start;
  58         int             advise = MADV_NORMAL, c;
  59         size_t          blocksize, sectsize;
  60
  61         while ((c = getopt(argc, argv, "drsw")) != EOF) {
  62                 switch (c) {
  63                 case 'd':       /* Don't need these pages */
  64                         advise = MADV_DONTNEED;
  65                         break;
  66                 case 'r':       /* Expect random page references */
  67                         advise = MADV_RANDOM;
  68                         break;
  69                 case 's':       /* Expect sequential page references */
  70                         advise = MADV_SEQUENTIAL;
  71                         break;
  72                 case 'w':       /* Will need these pages */
  73                         advise = MADV_WILLNEED;
  74                         break;
  75                 default:
  76                         return command_usage(&madvise_cmd);
  77                 }
  78         }
  79
  80         if (optind == argc) {
  81                 offset = mapping->offset;
  82                 length = mapping->length;
  83         } else if (optind == argc - 2) {
  84                 init_cvtnum(&blocksize, &sectsize);
  85                 offset = cvtnum(blocksize, sectsize, argv[optind]);
  86                 if (offset < 0) {
  87                         printf(_("non-numeric offset argument -- %s\n"),
  88                                 argv[optind]);
  89                         return 0;
  90                 }
  91                 optind++;
  92                 llength = cvtnum(blocksize, sectsize, argv[optind]);
  93                 if (llength < 0) {
  94                         printf(_("non-numeric length argument -- %s\n"),
  95                                 argv[optind]);
  96                         return 0;
  97                 } else if (llength > (size_t)llength) {
  98                         printf(_("length argument too large -- %lld\n"),
  99                                 (long long)llength);
 100                         return 0;
 101                 } else
 102                         length = (size_t)llength;
 103         } else {
 104                 return command_usage(&madvise_cmd);
 105         }
 106
 107         start = check_mapping_range(mapping, offset, length, 1);
 108         if (!start)
 109                 return 0;
 110
 111         if (madvise(start, length, advise) < 0) {
 112                 perror("madvise");
 113                 return 0;
 114         }
 115         return 0;
 116 }
 117
 118 void
 119 madvise_init(void)
 120 {
 121         madvise_cmd.name = "madvise";
 122         madvise_cmd.altname = "ma";
 123         madvise_cmd.cfunc = madvise_f;
 124         madvise_cmd.argmin = 0;
 125         madvise_cmd.argmax = -1;
 126         madvise_cmd.flags = CMD_NOFILE_OK | CMD_FOREIGN_OK;
 127         madvise_cmd.args = _("[-drsw] [off len]");
 128         madvise_cmd.oneline = _("give advice about use of memory");
 129         madvise_cmd.help = madvise_help;
 130
 131         add_command(&madvise_cmd);
 132 }