ia64/linux-2.6.18-xen.hg

view arch/mips/sgi-ip27/ip27-klconfig.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 * Copyright (C) 1999, 2000 Ralf Baechle (ralf@gnu.org)
3 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
4 */
5 #include <linux/init.h>
6 #include <linux/kernel.h>
7 #include <linux/sched.h>
8 #include <linux/interrupt.h>
9 #include <linux/kernel_stat.h>
10 #include <linux/param.h>
11 #include <linux/timex.h>
12 #include <linux/mm.h>
14 #include <asm/sn/klconfig.h>
15 #include <asm/sn/arch.h>
16 #include <asm/sn/gda.h>
18 klinfo_t *find_component(lboard_t *brd, klinfo_t *kli, unsigned char struct_type)
19 {
20 int index, j;
22 if (kli == (klinfo_t *)NULL) {
23 index = 0;
24 } else {
25 for (j = 0; j < KLCF_NUM_COMPS(brd); j++)
26 if (kli == KLCF_COMP(brd, j))
27 break;
28 index = j;
29 if (index == KLCF_NUM_COMPS(brd)) {
30 printk("find_component: Bad pointer: 0x%p\n", kli);
31 return (klinfo_t *)NULL;
32 }
33 index++; /* next component */
34 }
36 for (; index < KLCF_NUM_COMPS(brd); index++) {
37 kli = KLCF_COMP(brd, index);
38 if (KLCF_COMP_TYPE(kli) == struct_type)
39 return kli;
40 }
42 /* Didn't find it. */
43 return (klinfo_t *)NULL;
44 }
46 klinfo_t *find_first_component(lboard_t *brd, unsigned char struct_type)
47 {
48 return find_component(brd, (klinfo_t *)NULL, struct_type);
49 }
51 lboard_t * find_lboard(lboard_t *start, unsigned char brd_type)
52 {
53 /* Search all boards stored on this node. */
54 while (start) {
55 if (start->brd_type == brd_type)
56 return start;
57 start = KLCF_NEXT(start);
58 }
59 /* Didn't find it. */
60 return (lboard_t *)NULL;
61 }
63 lboard_t * find_lboard_class(lboard_t *start, unsigned char brd_type)
64 {
65 /* Search all boards stored on this node. */
66 while (start) {
67 if (KLCLASS(start->brd_type) == KLCLASS(brd_type))
68 return start;
69 start = KLCF_NEXT(start);
70 }
72 /* Didn't find it. */
73 return (lboard_t *)NULL;
74 }
76 cnodeid_t get_cpu_cnode(cpuid_t cpu)
77 {
78 return CPUID_TO_COMPACT_NODEID(cpu);
79 }
81 klcpu_t * nasid_slice_to_cpuinfo(nasid_t nasid, int slice)
82 {
83 lboard_t *brd;
84 klcpu_t *acpu;
86 if (!(brd = find_lboard((lboard_t *)KL_CONFIG_INFO(nasid), KLTYPE_IP27)))
87 return (klcpu_t *)NULL;
89 if (!(acpu = (klcpu_t *)find_first_component(brd, KLSTRUCT_CPU)))
90 return (klcpu_t *)NULL;
92 do {
93 if ((acpu->cpu_info.physid) == slice)
94 return acpu;
95 } while ((acpu = (klcpu_t *)find_component(brd, (klinfo_t *)acpu,
96 KLSTRUCT_CPU)));
97 return (klcpu_t *)NULL;
98 }
100 klcpu_t * sn_get_cpuinfo(cpuid_t cpu)
101 {
102 nasid_t nasid;
103 int slice;
104 klcpu_t *acpu;
105 gda_t *gdap = GDA;
106 cnodeid_t cnode;
108 if (!(cpu < MAXCPUS)) {
109 printk("sn_get_cpuinfo: illegal cpuid 0x%lx\n", cpu);
110 return NULL;
111 }
113 cnode = get_cpu_cnode(cpu);
114 if (cnode == INVALID_CNODEID)
115 return NULL;
117 if ((nasid = gdap->g_nasidtable[cnode]) == INVALID_NASID)
118 return NULL;
120 for (slice = 0; slice < CPUS_PER_NODE; slice++) {
121 acpu = nasid_slice_to_cpuinfo(nasid, slice);
122 if (acpu && acpu->cpu_info.virtid == cpu)
123 return acpu;
124 }
125 return NULL;
126 }
128 int get_cpu_slice(cpuid_t cpu)
129 {
130 klcpu_t *acpu;
132 if ((acpu = sn_get_cpuinfo(cpu)) == NULL)
133 return -1;
134 return acpu->cpu_info.physid;
135 }