ia64/linux-2.6.18-xen.hg

view drivers/zorro/proc.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: proc.c,v 1.1.2.1 1998/06/07 23:21:01 geert Exp $
3 *
4 * Procfs interface for the Zorro bus.
5 *
6 * Copyright (C) 1998-2003 Geert Uytterhoeven
7 *
8 * Heavily based on the procfs interface for the PCI bus, which is
9 *
10 * Copyright (C) 1997, 1998 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
11 */
13 #include <linux/types.h>
14 #include <linux/zorro.h>
15 #include <linux/proc_fs.h>
16 #include <linux/init.h>
17 #include <linux/smp_lock.h>
18 #include <asm/uaccess.h>
19 #include <asm/amigahw.h>
20 #include <asm/setup.h>
22 static loff_t
23 proc_bus_zorro_lseek(struct file *file, loff_t off, int whence)
24 {
25 loff_t new = -1;
27 lock_kernel();
28 switch (whence) {
29 case 0:
30 new = off;
31 break;
32 case 1:
33 new = file->f_pos + off;
34 break;
35 case 2:
36 new = sizeof(struct ConfigDev) + off;
37 break;
38 }
39 if (new < 0 || new > sizeof(struct ConfigDev)) {
40 unlock_kernel();
41 return -EINVAL;
42 }
43 unlock_kernel();
44 return (file->f_pos = new);
45 }
47 static ssize_t
48 proc_bus_zorro_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
49 {
50 struct inode *ino = file->f_dentry->d_inode;
51 struct proc_dir_entry *dp = PDE(ino);
52 struct zorro_dev *z = dp->data;
53 struct ConfigDev cd;
54 loff_t pos = *ppos;
56 if (pos >= sizeof(struct ConfigDev))
57 return 0;
58 if (nbytes >= sizeof(struct ConfigDev))
59 nbytes = sizeof(struct ConfigDev);
60 if (pos + nbytes > sizeof(struct ConfigDev))
61 nbytes = sizeof(struct ConfigDev) - pos;
63 /* Construct a ConfigDev */
64 memset(&cd, 0, sizeof(cd));
65 cd.cd_Rom = z->rom;
66 cd.cd_SlotAddr = z->slotaddr;
67 cd.cd_SlotSize = z->slotsize;
68 cd.cd_BoardAddr = (void *)zorro_resource_start(z);
69 cd.cd_BoardSize = zorro_resource_len(z);
71 if (copy_to_user(buf, &cd, nbytes))
72 return -EFAULT;
73 *ppos += nbytes;
75 return nbytes;
76 }
78 static struct file_operations proc_bus_zorro_operations = {
79 .llseek = proc_bus_zorro_lseek,
80 .read = proc_bus_zorro_read,
81 };
83 static int
84 get_zorro_dev_info(char *buf, char **start, off_t pos, int count)
85 {
86 u_int slot;
87 off_t at = 0;
88 int len, cnt;
90 for (slot = cnt = 0; slot < zorro_num_autocon && count > cnt; slot++) {
91 struct zorro_dev *z = &zorro_autocon[slot];
92 len = sprintf(buf, "%02x\t%08x\t%08lx\t%08lx\t%02x\n", slot,
93 z->id, zorro_resource_start(z),
94 zorro_resource_len(z), z->rom.er_Type);
95 at += len;
96 if (at >= pos) {
97 if (!*start) {
98 *start = buf + (pos - (at - len));
99 cnt = at - pos;
100 } else
101 cnt += len;
102 buf += len;
103 }
104 }
105 return (count > cnt) ? cnt : count;
106 }
108 static struct proc_dir_entry *proc_bus_zorro_dir;
110 static int __init zorro_proc_attach_device(u_int slot)
111 {
112 struct proc_dir_entry *entry;
113 char name[4];
115 sprintf(name, "%02x", slot);
116 entry = create_proc_entry(name, 0, proc_bus_zorro_dir);
117 if (!entry)
118 return -ENOMEM;
119 entry->proc_fops = &proc_bus_zorro_operations;
120 entry->data = &zorro_autocon[slot];
121 entry->size = sizeof(struct zorro_dev);
122 return 0;
123 }
125 static int __init zorro_proc_init(void)
126 {
127 u_int slot;
129 if (MACH_IS_AMIGA && AMIGAHW_PRESENT(ZORRO)) {
130 proc_bus_zorro_dir = proc_mkdir("zorro", proc_bus);
131 create_proc_info_entry("devices", 0, proc_bus_zorro_dir,
132 get_zorro_dev_info);
133 for (slot = 0; slot < zorro_num_autocon; slot++)
134 zorro_proc_attach_device(slot);
135 }
136 return 0;
137 }
139 __initcall(zorro_proc_init);