ia64/linux-2.6.18-xen.hg

view drivers/mtd/maps/autcpu12-nvram.c @ 897:329ea0ccb344

balloon: try harder to balloon up under memory pressure.

Currently if the balloon driver is unable to increase the guest's
reservation it assumes the failure was due to reaching its full
allocation, gives up on the ballooning operation and records the limit
it reached as the "hard limit". The driver will not try again until
the target is set again (even to the same value).

However it is possible that ballooning has in fact failed due to
memory pressure in the host and therefore it is desirable to keep
attempting to reach the target in case memory becomes available. The
most likely scenario is that some guests are ballooning down while
others are ballooning up and therefore there is temporary memory
pressure while things stabilise. You would not expect a well behaved
toolstack to ask a domain to balloon to more than its allocation nor
would you expect it to deliberately over-commit memory by setting
balloon targets which exceed the total host memory.

This patch drops the concept of a hard limit and causes the balloon
driver to retry increasing the reservation on a timer in the same
manner as when decreasing the reservation.

Also if we partially succeed in increasing the reservation
(i.e. receive less pages than we asked for) then we may as well keep
those pages rather than returning them to Xen.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Fri Jun 05 14:01:20 2009 +0100 (2009-06-05)
parents 831230e53067
children
line source
1 /*
2 * NV-RAM memory access on autcpu12
3 * (C) 2002 Thomas Gleixner (gleixner@autronix.de)
4 *
5 * $Id: autcpu12-nvram.c,v 1.9 2005/11/07 11:14:26 gleixner Exp $
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 *
21 */
23 #include <linux/module.h>
24 #include <linux/types.h>
25 #include <linux/kernel.h>
26 #include <linux/ioport.h>
27 #include <linux/init.h>
28 #include <asm/io.h>
29 #include <asm/sizes.h>
30 #include <asm/hardware.h>
31 #include <asm/arch/autcpu12.h>
32 #include <linux/mtd/mtd.h>
33 #include <linux/mtd/map.h>
34 #include <linux/mtd/partitions.h>
37 static struct mtd_info *sram_mtd;
39 struct map_info autcpu12_sram_map = {
40 .name = "SRAM",
41 .size = 32768,
42 .bankwidth = 4,
43 .phys = 0x12000000,
44 };
46 static int __init init_autcpu12_sram (void)
47 {
48 int err, save0, save1;
50 autcpu12_sram_map.virt = ioremap(0x12000000, SZ_128K);
51 if (!autcpu12_sram_map.virt) {
52 printk("Failed to ioremap autcpu12 NV-RAM space\n");
53 err = -EIO;
54 goto out;
55 }
56 simple_map_init(&autcpu_sram_map);
58 /*
59 * Check for 32K/128K
60 * read ofs 0
61 * read ofs 0x10000
62 * Write complement to ofs 0x100000
63 * Read and check result on ofs 0x0
64 * Restore contents
65 */
66 save0 = map_read32(&autcpu12_sram_map,0);
67 save1 = map_read32(&autcpu12_sram_map,0x10000);
68 map_write32(&autcpu12_sram_map,~save0,0x10000);
69 /* if we find this pattern on 0x0, we have 32K size
70 * restore contents and exit
71 */
72 if ( map_read32(&autcpu12_sram_map,0) != save0) {
73 map_write32(&autcpu12_sram_map,save0,0x0);
74 goto map;
75 }
76 /* We have a 128K found, restore 0x10000 and set size
77 * to 128K
78 */
79 map_write32(&autcpu12_sram_map,save1,0x10000);
80 autcpu12_sram_map.size = SZ_128K;
82 map:
83 sram_mtd = do_map_probe("map_ram", &autcpu12_sram_map);
84 if (!sram_mtd) {
85 printk("NV-RAM probe failed\n");
86 err = -ENXIO;
87 goto out_ioremap;
88 }
90 sram_mtd->owner = THIS_MODULE;
91 sram_mtd->erasesize = 16;
93 if (add_mtd_device(sram_mtd)) {
94 printk("NV-RAM device addition failed\n");
95 err = -ENOMEM;
96 goto out_probe;
97 }
99 printk("NV-RAM device size %ldKiB registered on AUTCPU12\n",autcpu12_sram_map.size/SZ_1K);
101 return 0;
103 out_probe:
104 map_destroy(sram_mtd);
105 sram_mtd = 0;
107 out_ioremap:
108 iounmap((void *)autcpu12_sram_map.virt);
109 out:
110 return err;
111 }
113 static void __exit cleanup_autcpu12_maps(void)
114 {
115 if (sram_mtd) {
116 del_mtd_device(sram_mtd);
117 map_destroy(sram_mtd);
118 iounmap((void *)autcpu12_sram_map.virt);
119 }
120 }
122 module_init(init_autcpu12_sram);
123 module_exit(cleanup_autcpu12_maps);
125 MODULE_AUTHOR("Thomas Gleixner");
126 MODULE_DESCRIPTION("autcpu12 NV-RAM map driver");
127 MODULE_LICENSE("GPL");