view Documentation/networking/fore200e.txt @ 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
line source
2 FORE Systems PCA-200E/SBA-200E ATM NIC driver
3 ---------------------------------------------
5 This driver adds support for the FORE Systems 200E-series ATM adapters
6 to the Linux operating system. It is based on the earlier PCA-200E driver
7 written by Uwe Dannowski.
9 The driver simultaneously supports PCA-200E and SBA-200E adapters on
10 i386, alpha (untested), powerpc, sparc and sparc64 archs.
12 The intent is to enable the use of different models of FORE adapters at the
13 same time, by hosts that have several bus interfaces (such as PCI+SBUS,
16 Only PCI and SBUS devices are currently supported by the driver, but support
17 for other bus interfaces such as EISA should not be too hard to add (this may
18 be more tricky for the MCA bus, though, as FORE made some MCA-specific
19 modifications to the adapter's AALI interface).
22 Firmware Copyright Notice
23 -------------------------
25 Please read the fore200e_firmware_copyright file present
26 in the linux/drivers/atm directory for details and restrictions.
29 Firmware Updates
30 ----------------
32 The FORE Systems 200E-series driver is shipped with firmware data being
33 uploaded to the ATM adapters at system boot time or at module loading time.
34 The supplied firmware images should work with all adapters.
36 However, if you encounter problems (the firmware doesn't start or the driver
37 is unable to read the PROM data), you may consider trying another firmware
38 version. Alternative binary firmware images can be found somewhere on the
39 ForeThought CD-ROM supplied with your adapter by FORE Systems.
41 You can also get the latest firmware images from FORE Systems at
42 http://www.fore.com. Register TACTics Online and go to
43 the 'software updates' pages. The firmware binaries are part of
44 the various ForeThought software distributions.
46 Notice that different versions of the PCA-200E firmware exist, depending
47 on the endianess of the host architecture. The driver is shipped with
48 both little and big endian PCA firmware images.
50 Name and location of the new firmware images can be set at kernel
51 configuration time:
53 1. Copy the new firmware binary files (with .bin, .bin1 or .bin2 suffix)
54 to some directory, such as linux/drivers/atm.
56 2. Reconfigure your kernel to set the new firmware name and location.
57 Expected pathnames are absolute or relative to the drivers/atm directory.
59 3. Rebuild and re-install your kernel or your module.
62 Feedback
63 --------
65 Feedback is welcome. Please send success stories/bug reports/
66 patches/improvement/comments/flames to <lizzi@cnam.fr>.