ia64/linux-2.6.18-xen.hg

view Documentation/arm/IXP4xx @ 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
2 -------------------------------------------------------------------------
3 Release Notes for Linux on Intel's IXP4xx Network Processor
5 Maintained by Deepak Saxena <dsaxena@plexity.net>
6 -------------------------------------------------------------------------
8 1. Overview
10 Intel's IXP4xx network processor is a highly integrated SOC that
11 is targeted for network applications, though it has become popular
12 in industrial control and other areas due to low cost and power
13 consumption. The IXP4xx family currently consists of several processors
14 that support different network offload functions such as encryption,
15 routing, firewalling, etc. The IXP46x family is an updated version which
16 supports faster speeds, new memory and flash configurations, and more
17 integration such as an on-chip I2C controller.
19 For more information on the various versions of the CPU, see:
21 http://developer.intel.com/design/network/products/npfamily/ixp4xx.htm
23 Intel also made the IXCP1100 CPU for sometime which is an IXP4xx
24 stripped of much of the network intelligence.
26 2. Linux Support
28 Linux currently supports the following features on the IXP4xx chips:
30 - Dual serial ports
31 - PCI interface
32 - Flash access (MTD/JFFS)
33 - I2C through GPIO on IXP42x
34 - GPIO for input/output/interrupts
35 See include/asm-arm/arch-ixp4xx/platform.h for access functions.
36 - Timers (watchdog, OS)
38 The following components of the chips are not supported by Linux and
39 require the use of Intel's propietary CSR softare:
41 - USB device interface
42 - Network interfaces (HSS, Utopia, NPEs, etc)
43 - Network offload functionality
45 If you need to use any of the above, you need to download Intel's
46 software from:
48 http://developer.intel.com/design/network/products/npfamily/ixp425swr1.htm
50 DO NOT POST QUESTIONS TO THE LINUX MAILING LISTS REGARDING THE PROPIETARY
51 SOFTWARE.
53 There are several websites that provide directions/pointers on using
54 Intel's software:
56 http://ixp4xx-osdg.sourceforge.net/
57 Open Source Developer's Guide for using uClinux and the Intel libraries
59 http://gatewaymaker.sourceforge.net/
60 Simple one page summary of building a gateway using an IXP425 and Linux
62 http://ixp425.sourceforge.net/
63 ATM device driver for IXP425 that relies on Intel's libraries
65 3. Known Issues/Limitations
67 3a. Limited inbound PCI window
69 The IXP4xx family allows for up to 256MB of memory but the PCI interface
70 can only expose 64MB of that memory to the PCI bus. This means that if
71 you are running with > 64MB, all PCI buffers outside of the accessible
72 range will be bounced using the routines in arch/arm/common/dmabounce.c.
74 3b. Limited outbound PCI window
76 IXP4xx provides two methods of accessing PCI memory space:
78 1) A direct mapped window from 0x48000000 to 0x4bffffff (64MB).
79 To access PCI via this space, we simply ioremap() the BAR
80 into the kernel and we can use the standard read[bwl]/write[bwl]
81 macros. This is the preffered method due to speed but it
82 limits the system to just 64MB of PCI memory. This can be
83 problamatic if using video cards and other memory-heavy devices.
85 2) If > 64MB of memory space is required, the IXP4xx can be
86 configured to use indirect registers to access PCI This allows
87 for up to 128MB (0x48000000 to 0x4fffffff) of memory on the bus.
88 The disadvantage of this is that every PCI access requires
89 three local register accesses plus a spinlock, but in some
90 cases the performance hit is acceptable. In addition, you cannot
91 mmap() PCI devices in this case due to the indirect nature
92 of the PCI window.
94 By default, the direct method is used for performance reasons. If
95 you need more PCI memory, enable the IXP4XX_INDIRECT_PCI config option.
97 3c. GPIO as Interrupts
99 Currently the code only handles level-sensitive GPIO interrupts
101 4. Supported platforms
103 ADI Engineering Coyote Gateway Reference Platform
104 http://www.adiengineering.com/productsCoyote.html
106 The ADI Coyote platform is reference design for those building
107 small residential/office gateways. One NPE is connected to a 10/100
108 interface, one to 4-port 10/100 switch, and the third to and ADSL
109 interface. In addition, it also supports to POTs interfaces connected
110 via SLICs. Note that those are not supported by Linux ATM. Finally,
111 the platform has two mini-PCI slots used for 802.11[bga] cards.
112 Finally, there is an IDE port hanging off the expansion bus.
114 Gateworks Avila Network Platform
115 http://www.gateworks.com/avila_sbc.htm
117 The Avila platform is basically and IXDP425 with the 4 PCI slots
118 replaced with mini-PCI slots and a CF IDE interface hanging off
119 the expansion bus.
121 Intel IXDP425 Development Platform
122 http://developer.intel.com/design/network/products/npfamily/ixdp425.htm
124 This is Intel's standard reference platform for the IXDP425 and is
125 also known as the Richfield board. It contains 4 PCI slots, 16MB
126 of flash, two 10/100 ports and one ADSL port.
128 Intel IXDP465 Development Platform
129 http://developer.intel.com/design/network/products/npfamily/ixdp465.htm
131 This is basically an IXDP425 with an IXP465 and 32M of flash instead
132 of just 16.
134 Intel IXDPG425 Development Platform
136 This is basically and ADI Coyote board with a NEC EHCI controller
137 added. One issue with this board is that the mini-PCI slots only
138 have the 3.3v line connected, so you can't use a PCI to mini-PCI
139 adapter with an E100 card. So to NFS root you need to use either
140 the CSR or a WiFi card and a ramdisk that BOOTPs and then does
141 a pivot_root to NFS.
143 Motorola PrPMC1100 Processor Mezanine Card
144 http://www.fountainsys.com/datasheet/PrPMC1100.pdf
146 The PrPMC1100 is based on the IXCP1100 and is meant to plug into
147 and IXP2400/2800 system to act as the system controller. It simply
148 contains a CPU and 16MB of flash on the board and needs to be
149 plugged into a carrier board to function. Currently Linux only
150 supports the Motorola PrPMC carrier board for this platform.
151 See https://mcg.motorola.com/us/ds/pdf/ds0144.pdf for info
152 on the carrier board.
154 5. TODO LIST
156 - Add support for Coyote IDE
157 - Add support for edge-based GPIO interrupts
158 - Add support for CF IDE on expansion bus
160 6. Thanks
162 The IXP4xx work has been funded by Intel Corp. and MontaVista Software, Inc.
164 The following people have contributed patches/comments/etc:
166 Lennerty Buytenhek
167 Lutz Jaenicke
168 Justin Mayfield
169 Robert E. Ranslam
170 [I know I've forgotten others, please email me to be added]
172 -------------------------------------------------------------------------
174 Last Update: 01/04/2005