ia64/linux-2.6.18-xen.hg

view arch/mips/pci/pci-yosemite.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 by Ralf Baechle (ralf@linux-mips.org)
7 */
8 #include <linux/init.h>
9 #include <linux/kernel.h>
10 #include <linux/types.h>
11 #include <linux/pci.h>
12 #include <asm/titan_dep.h>
14 extern struct pci_ops titan_pci_ops;
16 static struct resource py_mem_resource = {
17 .start = 0xe0000000UL,
18 .end = 0xe3ffffffUL,
19 .name = "Titan PCI MEM",
20 .flags = IORESOURCE_MEM
21 };
23 /*
24 * PMON really reserves 16MB of I/O port space but that's stupid, nothing
25 * needs that much since allocations are limited to 256 bytes per device
26 * anyway. So we just claim 64kB here.
27 */
28 #define TITAN_IO_SIZE 0x0000ffffUL
29 #define TITAN_IO_BASE 0xe8000000UL
31 static struct resource py_io_resource = {
32 .start = 0x00001000UL,
33 .end = TITAN_IO_SIZE - 1,
34 .name = "Titan IO MEM",
35 .flags = IORESOURCE_IO,
36 };
38 static struct pci_controller py_controller = {
39 .pci_ops = &titan_pci_ops,
40 .mem_resource = &py_mem_resource,
41 .mem_offset = 0x00000000UL,
42 .io_resource = &py_io_resource,
43 .io_offset = 0x00000000UL
44 };
46 static char ioremap_failed[] __initdata = "Could not ioremap I/O port range";
48 static int __init pmc_yosemite_setup(void)
49 {
50 unsigned long io_v_base;
52 io_v_base = (unsigned long) ioremap(TITAN_IO_BASE, TITAN_IO_SIZE);
53 if (!io_v_base)
54 panic(ioremap_failed);
56 set_io_port_base(io_v_base);
57 TITAN_WRITE(RM9000x2_OCD_LKM7, TITAN_READ(RM9000x2_OCD_LKM7) | 1);
59 ioport_resource.end = TITAN_IO_SIZE - 1;
61 register_pci_controller(&py_controller);
63 return 0;
64 }
66 arch_initcall(pmc_yosemite_setup);