ia64/linux-2.6.18-xen.hg

view arch/mips/pci/pci-ev96100.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 2000 MontaVista Software Inc.
3 * Author: MontaVista Software, Inc.
4 * ppopov@mvista.com or source@mvista.com
5 *
6 * Carsten Langgaard, carstenl@mips.com
7 * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
8 *
9 * Copyright (C) 2004 by Ralf Baechle (ralf@linux-mips.org)
10 *
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2 of the License, or (at your
14 * option) any later version.
15 *
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
19 * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
22 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
23 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 * You should have received a copy of the GNU General Public License along
28 * with this program; if not, write to the Free Software Foundation, Inc.,
29 * 675 Mass Ave, Cambridge, MA 02139, USA.
30 */
31 #include <linux/types.h>
32 #include <linux/pci.h>
33 #include <linux/kernel.h>
34 #include <linux/init.h>
36 static struct resource pci_io_resource = {
37 .name = "io pci IO space",
38 .start = 0x10000000,
39 .end = 0x11ffffff,
40 .flags = IORESOURCE_IO
41 };
43 static struct resource pci_mem_resource = {
44 .name = "ext pci memory space",
45 .start = 0x12000000,
46 .end = 0x13ffffff,
47 .flags = IORESOURCE_MEM
48 };
50 extern struct pci_ops gt96100_pci_ops;
52 struct pci_controller ev96100_controller = {
53 .pci_ops = &gt96100_pci_ops,
54 .io_resource = &pci_io_resource,
55 .mem_resource = &pci_mem_resource,
56 };
58 static void ev96100_pci_init(void)
59 {
60 register_pci_controller(&ev96100_controller);
61 }
63 arch_initcall(ev96100_pci_init);