ia64/linux-2.6.18-xen.hg

view drivers/mtd/maps/walnut.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 * $Id: walnut.c,v 1.3 2005/11/07 11:14:29 gleixner Exp $
3 *
4 * Mapping for Walnut flash
5 * (used ebony.c as a "framework")
6 *
7 * Heikki Lindholm <holindho@infradead.org>
8 *
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 */
16 #include <linux/module.h>
17 #include <linux/types.h>
18 #include <linux/kernel.h>
19 #include <linux/init.h>
20 #include <linux/mtd/mtd.h>
21 #include <linux/mtd/map.h>
22 #include <linux/mtd/partitions.h>
23 #include <asm/io.h>
24 #include <asm/ibm4xx.h>
25 #include <platforms/4xx/walnut.h>
27 /* these should be in platforms/4xx/walnut.h ? */
28 #define WALNUT_FLASH_ONBD_N(x) (x & 0x02)
29 #define WALNUT_FLASH_SRAM_SEL(x) (x & 0x01)
30 #define WALNUT_FLASH_LOW 0xFFF00000
31 #define WALNUT_FLASH_HIGH 0xFFF80000
32 #define WALNUT_FLASH_SIZE 0x80000
34 static struct mtd_info *flash;
36 static struct map_info walnut_map = {
37 .name = "Walnut flash",
38 .size = WALNUT_FLASH_SIZE,
39 .bankwidth = 1,
40 };
42 /* Actually, OpenBIOS is the last 128 KiB of the flash - better
43 * partitioning could be made */
44 static struct mtd_partition walnut_partitions[] = {
45 {
46 .name = "OpenBIOS",
47 .offset = 0x0,
48 .size = WALNUT_FLASH_SIZE,
49 /*.mask_flags = MTD_WRITEABLE, */ /* force read-only */
50 }
51 };
53 int __init init_walnut(void)
54 {
55 u8 fpga_brds1;
56 void *fpga_brds1_adr;
57 void *fpga_status_adr;
58 unsigned long flash_base;
60 /* this should already be mapped (platform/4xx/walnut.c) */
61 fpga_status_adr = ioremap(WALNUT_FPGA_BASE, 8);
62 if (!fpga_status_adr)
63 return -ENOMEM;
65 fpga_brds1_adr = fpga_status_adr+5;
66 fpga_brds1 = readb(fpga_brds1_adr);
67 /* iounmap(fpga_status_adr); */
69 if (WALNUT_FLASH_ONBD_N(fpga_brds1)) {
70 printk("The on-board flash is disabled (U79 sw 5)!");
71 return -EIO;
72 }
73 if (WALNUT_FLASH_SRAM_SEL(fpga_brds1))
74 flash_base = WALNUT_FLASH_LOW;
75 else
76 flash_base = WALNUT_FLASH_HIGH;
78 walnut_map.phys = flash_base;
79 walnut_map.virt =
80 (void __iomem *)ioremap(flash_base, walnut_map.size);
82 if (!walnut_map.virt) {
83 printk("Failed to ioremap flash.\n");
84 return -EIO;
85 }
87 simple_map_init(&walnut_map);
89 flash = do_map_probe("jedec_probe", &walnut_map);
90 if (flash) {
91 flash->owner = THIS_MODULE;
92 add_mtd_partitions(flash, walnut_partitions,
93 ARRAY_SIZE(walnut_partitions));
94 } else {
95 printk("map probe failed for flash\n");
96 return -ENXIO;
97 }
99 return 0;
100 }
102 static void __exit cleanup_walnut(void)
103 {
104 if (flash) {
105 del_mtd_partitions(flash);
106 map_destroy(flash);
107 }
109 if (walnut_map.virt) {
110 iounmap((void *)walnut_map.virt);
111 walnut_map.virt = 0;
112 }
113 }
115 module_init(init_walnut);
116 module_exit(cleanup_walnut);
118 MODULE_LICENSE("GPL");
119 MODULE_AUTHOR("Heikki Lindholm <holindho@infradead.org>");
120 MODULE_DESCRIPTION("MTD map and partitions for IBM 405GP Walnut boards");