ia64/linux-2.6.18-xen.hg

view drivers/mtd/maps/pq2fads.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 * drivers/mtd/maps/pq2fads.c
3 *
4 * Mapping for the flash SIMM on 8272ADS and PQ2FADS board
5 *
6 * Author: Vitaly Bordug <vbordug@ru.mvista.com>
7 *
8 * 2005 (c) MontaVista Software, Inc. This file is licensed under
9 * the terms of the GNU General Public License version 2. This program
10 * is licensed "as is" without any warranty of any kind, whether express
11 * or implied.
12 */
14 #include <linux/module.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <asm/io.h>
19 #include <asm/ppcboot.h>
20 #include <linux/mtd/mtd.h>
21 #include <linux/mtd/map.h>
22 #include <linux/mtd/partitions.h>
23 #include <linux/mtd/physmap.h>
25 /*
26 NOTE: bank width and interleave relative to the installed flash
27 should have been chosen within MTD_CFI_GEOMETRY options.
28 */
29 #define PQ2FADS_BANK_WIDTH 4
31 static struct mtd_partition pq2fads_partitions[] = {
32 {
33 #ifdef CONFIG_ADS8272
34 .name = "HRCW",
35 .size = 0x40000,
36 .offset = 0,
37 .mask_flags = MTD_WRITEABLE, /* force read-only */
38 }, {
39 .name = "User FS",
40 .size = 0x5c0000,
41 .offset = 0x40000,
42 #else
43 .name = "User FS",
44 .size = 0x600000,
45 .offset = 0,
46 #endif
47 }, {
48 .name = "uImage",
49 .size = 0x100000,
50 .offset = 0x600000,
51 .mask_flags = MTD_WRITEABLE, /* force read-only */
52 }, {
53 .name = "bootloader",
54 .size = 0x40000,
55 .offset = 0x700000,
56 .mask_flags = MTD_WRITEABLE, /* force read-only */
57 }, {
58 .name = "bootloader env",
59 .size = 0x40000,
60 .offset = 0x740000,
61 .mask_flags = MTD_WRITEABLE, /* force read-only */
62 }
63 };
66 /* pointer to MPC885ADS board info data */
67 extern unsigned char __res[];
69 static int __init init_pq2fads_mtd(void)
70 {
71 bd_t *bd = (bd_t *)__res;
72 physmap_configure(bd->bi_flashstart, bd->bi_flashsize, PQ2FADS_BANK_WIDTH, NULL);
74 physmap_set_partitions(pq2fads_partitions,
75 sizeof (pq2fads_partitions) /
76 sizeof (pq2fads_partitions[0]));
77 return 0;
78 }
80 static void __exit cleanup_pq2fads_mtd(void)
81 {
82 }
84 module_init(init_pq2fads_mtd);
85 module_exit(cleanup_pq2fads_mtd);
87 MODULE_LICENSE("GPL");
88 MODULE_DESCRIPTION("MTD map and partitions for MPC8272ADS boards");