ia64/linux-2.6.18-xen.hg

view drivers/mtd/maps/tsunami_flash.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 * tsunami_flash.c
3 *
4 * flash chip on alpha ds10...
5 * $Id: tsunami_flash.c,v 1.10 2005/11/07 11:14:29 gleixner Exp $
6 */
7 #include <asm/io.h>
8 #include <asm/core_tsunami.h>
9 #include <linux/init.h>
10 #include <linux/mtd/map.h>
11 #include <linux/mtd/mtd.h>
13 #define FLASH_ENABLE_PORT 0x00C00001
14 #define FLASH_ENABLE_BYTE 0x01
15 #define FLASH_DISABLE_BYTE 0x00
17 #define MAX_TIG_FLASH_SIZE (12*1024*1024)
18 static inline map_word tsunami_flash_read8(struct map_info *map, unsigned long offset)
19 {
20 map_word val;
21 val.x[0] = tsunami_tig_readb(offset);
22 return val;
23 }
25 static void tsunami_flash_write8(struct map_info *map, map_word value, unsigned long offset)
26 {
27 tsunami_tig_writeb(value.x[0], offset);
28 }
30 static void tsunami_flash_copy_from(
31 struct map_info *map, void *addr, unsigned long offset, ssize_t len)
32 {
33 unsigned char *dest;
34 dest = addr;
35 while(len && (offset < MAX_TIG_FLASH_SIZE)) {
36 *dest = tsunami_tig_readb(offset);
37 offset++;
38 dest++;
39 len--;
40 }
41 }
43 static void tsunami_flash_copy_to(
44 struct map_info *map, unsigned long offset,
45 const void *addr, ssize_t len)
46 {
47 const unsigned char *src;
48 src = addr;
49 while(len && (offset < MAX_TIG_FLASH_SIZE)) {
50 tsunami_tig_writeb(*src, offset);
51 offset++;
52 src++;
53 len--;
54 }
55 }
57 /*
58 * Deliberately don't provide operations wider than 8 bits. I don't
59 * have then and it scares me to think how you could mess up if
60 * you tried to use them. Buswidth is correctly so I'm safe.
61 */
62 static struct map_info tsunami_flash_map = {
63 .name = "flash chip on the Tsunami TIG bus",
64 .size = MAX_TIG_FLASH_SIZE,
65 .phys = NO_XIP,
66 .bankwidth = 1,
67 .read = tsunami_flash_read8,
68 .copy_from = tsunami_flash_copy_from,
69 .write = tsunami_flash_write8,
70 .copy_to = tsunami_flash_copy_to,
71 };
73 static struct mtd_info *tsunami_flash_mtd;
75 static void __exit cleanup_tsunami_flash(void)
76 {
77 struct mtd_info *mtd;
78 mtd = tsunami_flash_mtd;
79 if (mtd) {
80 del_mtd_device(mtd);
81 map_destroy(mtd);
82 }
83 tsunami_flash_mtd = 0;
84 }
87 static int __init init_tsunami_flash(void)
88 {
89 static const char *rom_probe_types[] = { "cfi_probe", "jedec_probe", "map_rom", NULL };
90 char **type;
92 tsunami_tig_writeb(FLASH_ENABLE_BYTE, FLASH_ENABLE_PORT);
94 tsunami_flash_mtd = 0;
95 type = rom_probe_types;
96 for(; !tsunami_flash_mtd && *type; type++) {
97 tsunami_flash_mtd = do_map_probe(*type, &tsunami_flash_map);
98 }
99 if (tsunami_flash_mtd) {
100 tsunami_flash_mtd->owner = THIS_MODULE;
101 add_mtd_device(tsunami_flash_mtd);
102 return 0;
103 }
104 return -ENXIO;
105 }
107 module_init(init_tsunami_flash);
108 module_exit(cleanup_tsunami_flash);