ia64/linux-2.6.18-xen.hg

view arch/mips/pci/ops-vr41xx.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 * ops-vr41xx.c, PCI configuration routines for the PCIU of NEC VR4100 series.
3 *
4 * Copyright (C) 2001-2003 MontaVista Software Inc.
5 * Author: Yoichi Yuasa <yyuasa@mvista.com or source@mvista.com>
6 * Copyright (C) 2004-2005 Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22 /*
23 * Changes:
24 * MontaVista Software Inc. <yyuasa@mvista.com> or <source@mvista.com>
25 * - New creation, NEC VR4122 and VR4131 are supported.
26 */
27 #include <linux/pci.h>
28 #include <linux/types.h>
30 #include <asm/io.h>
32 #define PCICONFDREG (void __iomem *)KSEG1ADDR(0x0f000c14)
33 #define PCICONFAREG (void __iomem *)KSEG1ADDR(0x0f000c18)
35 static inline int set_pci_configuration_address(unsigned char number,
36 unsigned int devfn, int where)
37 {
38 if (number == 0) {
39 /*
40 * Type 0 configuration
41 */
42 if (PCI_SLOT(devfn) < 11 || where > 0xff)
43 return -EINVAL;
45 writel((1U << PCI_SLOT(devfn)) | (PCI_FUNC(devfn) << 8) |
46 (where & 0xfc), PCICONFAREG);
47 } else {
48 /*
49 * Type 1 configuration
50 */
51 if (where > 0xff)
52 return -EINVAL;
54 writel(((uint32_t)number << 16) | ((devfn & 0xff) << 8) |
55 (where & 0xfc) | 1U, PCICONFAREG);
56 }
58 return 0;
59 }
61 static int pci_config_read(struct pci_bus *bus, unsigned int devfn, int where,
62 int size, uint32_t *val)
63 {
64 uint32_t data;
66 *val = 0xffffffffU;
67 if (set_pci_configuration_address(bus->number, devfn, where) < 0)
68 return PCIBIOS_DEVICE_NOT_FOUND;
70 data = readl(PCICONFDREG);
72 switch (size) {
73 case 1:
74 *val = (data >> ((where & 3) << 3)) & 0xffU;
75 break;
76 case 2:
77 *val = (data >> ((where & 2) << 3)) & 0xffffU;
78 break;
79 case 4:
80 *val = data;
81 break;
82 default:
83 return PCIBIOS_FUNC_NOT_SUPPORTED;
84 }
86 return PCIBIOS_SUCCESSFUL;
87 }
89 static int pci_config_write(struct pci_bus *bus, unsigned int devfn, int where,
90 int size, uint32_t val)
91 {
92 uint32_t data;
93 int shift;
95 if (set_pci_configuration_address(bus->number, devfn, where) < 0)
96 return PCIBIOS_DEVICE_NOT_FOUND;
98 data = readl(PCICONFDREG);
100 switch (size) {
101 case 1:
102 shift = (where & 3) << 3;
103 data &= ~(0xffU << shift);
104 data |= ((val & 0xffU) << shift);
105 break;
106 case 2:
107 shift = (where & 2) << 3;
108 data &= ~(0xffffU << shift);
109 data |= ((val & 0xffffU) << shift);
110 break;
111 case 4:
112 data = val;
113 break;
114 default:
115 return PCIBIOS_FUNC_NOT_SUPPORTED;
116 }
118 writel(data, PCICONFDREG);
120 return PCIBIOS_SUCCESSFUL;
121 }
123 struct pci_ops vr41xx_pci_ops = {
124 .read = pci_config_read,
125 .write = pci_config_write,
126 };