ia64/linux-2.6.18-xen.hg

view arch/sparc64/kernel/starfire.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 /* $Id: starfire.c,v 1.10 2001/04/14 21:13:45 davem Exp $
2 * starfire.c: Starfire/E10000 support.
3 *
4 * Copyright (C) 1998 David S. Miller (davem@redhat.com)
5 * Copyright (C) 2000 Anton Blanchard (anton@samba.org)
6 */
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
11 #include <asm/page.h>
12 #include <asm/oplib.h>
13 #include <asm/smp.h>
14 #include <asm/upa.h>
15 #include <asm/starfire.h>
17 /*
18 * A few places around the kernel check this to see if
19 * they need to call us to do things in a Starfire specific
20 * way.
21 */
22 int this_is_starfire = 0;
24 void check_if_starfire(void)
25 {
26 int ssnode = prom_finddevice("/ssp-serial");
27 if (ssnode != 0 && ssnode != -1)
28 this_is_starfire = 1;
29 }
31 void starfire_cpu_setup(void)
32 {
33 /* Currently, nothing to do. */
34 }
36 int starfire_hard_smp_processor_id(void)
37 {
38 return upa_readl(0x1fff40000d0UL);
39 }
41 /*
42 * Each Starfire board has 32 registers which perform translation
43 * and delivery of traditional interrupt packets into the extended
44 * Starfire hardware format. Essentially UPAID's now have 2 more
45 * bits than in all previous Sun5 systems.
46 */
47 struct starfire_irqinfo {
48 unsigned long imap_slots[32];
49 unsigned long tregs[32];
50 struct starfire_irqinfo *next;
51 int upaid, hwmid;
52 };
54 static struct starfire_irqinfo *sflist = NULL;
56 /* Beam me up Scott(McNeil)y... */
57 void starfire_hookup(int upaid)
58 {
59 struct starfire_irqinfo *p;
60 unsigned long treg_base, hwmid, i;
62 p = kmalloc(sizeof(*p), GFP_KERNEL);
63 if (!p) {
64 prom_printf("starfire_hookup: No memory, this is insane.\n");
65 prom_halt();
66 }
67 treg_base = 0x100fc000000UL;
68 hwmid = ((upaid & 0x3c) << 1) |
69 ((upaid & 0x40) >> 4) |
70 (upaid & 0x3);
71 p->hwmid = hwmid;
72 treg_base += (hwmid << 33UL);
73 treg_base += 0x200UL;
74 for (i = 0; i < 32; i++) {
75 p->imap_slots[i] = 0UL;
76 p->tregs[i] = treg_base + (i * 0x10UL);
77 /* Lets play it safe and not overwrite existing mappings */
78 if (upa_readl(p->tregs[i]) != 0)
79 p->imap_slots[i] = 0xdeadbeaf;
80 }
81 p->upaid = upaid;
82 p->next = sflist;
83 sflist = p;
84 }
86 unsigned int starfire_translate(unsigned long imap,
87 unsigned int upaid)
88 {
89 struct starfire_irqinfo *p;
90 unsigned int bus_hwmid;
91 unsigned int i;
93 bus_hwmid = (((unsigned long)imap) >> 33) & 0x7f;
94 for (p = sflist; p != NULL; p = p->next)
95 if (p->hwmid == bus_hwmid)
96 break;
97 if (p == NULL) {
98 prom_printf("XFIRE: Cannot find irqinfo for imap %016lx\n",
99 ((unsigned long)imap));
100 prom_halt();
101 }
102 for (i = 0; i < 32; i++) {
103 if (p->imap_slots[i] == imap ||
104 p->imap_slots[i] == 0UL)
105 break;
106 }
107 if (i == 32) {
108 printk("starfire_translate: Are you kidding me?\n");
109 panic("Lucy in the sky....");
110 }
111 p->imap_slots[i] = imap;
113 /* map to real upaid */
114 upaid = (((upaid & 0x3c) << 1) |
115 ((upaid & 0x40) >> 4) |
116 (upaid & 0x3));
118 upa_writel(upaid, p->tregs[i]);
120 return i;
121 }