ia64/linux-2.6.18-xen.hg

view arch/mips/oprofile/common.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 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2004, 2005 Ralf Baechle
7 * Copyright (C) 2005 MIPS Technologies, Inc.
8 */
9 #include <linux/errno.h>
10 #include <linux/init.h>
11 #include <linux/oprofile.h>
12 #include <linux/smp.h>
13 #include <asm/cpu-info.h>
15 #include "op_impl.h"
17 extern struct op_mips_model op_model_mipsxx_ops __attribute__((weak));
18 extern struct op_mips_model op_model_rm9000_ops __attribute__((weak));
20 static struct op_mips_model *model;
22 static struct op_counter_config ctr[20];
24 static int op_mips_setup(void)
25 {
26 /* Pre-compute the values to stuff in the hardware registers. */
27 model->reg_setup(ctr);
29 /* Configure the registers on all cpus. */
30 on_each_cpu(model->cpu_setup, NULL, 0, 1);
32 return 0;
33 }
35 static int op_mips_create_files(struct super_block * sb, struct dentry * root)
36 {
37 int i;
39 for (i = 0; i < model->num_counters; ++i) {
40 struct dentry *dir;
41 char buf[4];
43 snprintf(buf, sizeof buf, "%d", i);
44 dir = oprofilefs_mkdir(sb, root, buf);
46 oprofilefs_create_ulong(sb, dir, "enabled", &ctr[i].enabled);
47 oprofilefs_create_ulong(sb, dir, "event", &ctr[i].event);
48 oprofilefs_create_ulong(sb, dir, "count", &ctr[i].count);
49 oprofilefs_create_ulong(sb, dir, "kernel", &ctr[i].kernel);
50 oprofilefs_create_ulong(sb, dir, "user", &ctr[i].user);
51 oprofilefs_create_ulong(sb, dir, "exl", &ctr[i].exl);
52 /* Dummy. */
53 oprofilefs_create_ulong(sb, dir, "unit_mask", &ctr[i].unit_mask);
54 }
56 return 0;
57 }
59 static int op_mips_start(void)
60 {
61 on_each_cpu(model->cpu_start, NULL, 0, 1);
63 return 0;
64 }
66 static void op_mips_stop(void)
67 {
68 /* Disable performance monitoring for all counters. */
69 on_each_cpu(model->cpu_stop, NULL, 0, 1);
70 }
72 int __init oprofile_arch_init(struct oprofile_operations *ops)
73 {
74 struct op_mips_model *lmodel = NULL;
75 int res;
77 switch (current_cpu_data.cputype) {
78 case CPU_5KC:
79 case CPU_20KC:
80 case CPU_24K:
81 case CPU_25KF:
82 case CPU_34K:
83 case CPU_74K:
84 case CPU_SB1:
85 case CPU_SB1A:
86 lmodel = &op_model_mipsxx_ops;
87 break;
89 case CPU_RM9000:
90 lmodel = &op_model_rm9000_ops;
91 break;
92 };
94 if (!lmodel)
95 return -ENODEV;
97 res = lmodel->init();
98 if (res)
99 return res;
101 model = lmodel;
103 ops->create_files = op_mips_create_files;
104 ops->setup = op_mips_setup;
105 //ops->shutdown = op_mips_shutdown;
106 ops->start = op_mips_start;
107 ops->stop = op_mips_stop;
108 ops->cpu_type = lmodel->cpu_type;
110 printk(KERN_INFO "oprofile: using %s performance monitoring.\n",
111 lmodel->cpu_type);
113 return 0;
114 }
116 void oprofile_arch_exit(void)
117 {
118 if (model)
119 model->exit();
120 }