view drivers/block/Kconfig @ 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
1 #
2 # Block device driver configuration
3 #
5 menu "Block devices"
7 config BLK_DEV_FD
8 tristate "Normal floppy disk support"
9 depends on ARCH_MAY_HAVE_PC_FDC
10 ---help---
11 If you want to use the floppy disk drive(s) of your PC under Linux,
12 say Y. Information about this driver, especially important for IBM
13 Thinkpad users, is contained in <file:Documentation/floppy.txt>.
14 That file also contains the location of the Floppy driver FAQ as
15 well as location of the fdutils package used to configure additional
16 parameters of the driver at run time.
18 To compile this driver as a module, choose M here: the
19 module will be called floppy.
21 config AMIGA_FLOPPY
22 tristate "Amiga floppy support"
23 depends on AMIGA
25 config ATARI_FLOPPY
26 tristate "Atari floppy support"
27 depends on ATARI
29 config BLK_DEV_SWIM_IOP
30 bool "Macintosh IIfx/Quadra 900/Quadra 950 floppy support (EXPERIMENTAL)"
31 depends on MAC && EXPERIMENTAL && BROKEN
32 help
33 Say Y here to support the SWIM (Super Woz Integrated Machine) IOP
34 floppy controller on the Macintosh IIfx and Quadra 900/950.
36 config MAC_FLOPPY
37 tristate "Support for PowerMac floppy"
38 depends on PPC_PMAC && !PPC_PMAC64
39 help
40 If you have a SWIM-3 (Super Woz Integrated Machine 3; from Apple)
41 floppy controller, say Y here. Most commonly found in PowerMacs.
43 config BLK_DEV_PS2
44 tristate "PS/2 ESDI hard disk support"
45 depends on MCA && MCA_LEGACY && BROKEN
46 help
47 Say Y here if you have a PS/2 machine with a MCA bus and an ESDI
48 hard disk.
50 To compile this driver as a module, choose M here: the
51 module will be called ps2esdi.
53 config AMIGA_Z2RAM
54 tristate "Amiga Zorro II ramdisk support"
55 depends on ZORRO
56 help
57 This enables support for using Chip RAM and Zorro II RAM as a
58 ramdisk or as a swap partition. Say Y if you want to include this
59 driver in the kernel.
61 To compile this driver as a module, choose M here: the
62 module will be called z2ram.
64 config ATARI_ACSI
65 tristate "Atari ACSI support"
66 depends on ATARI && BROKEN
67 ---help---
68 This enables support for the Atari ACSI interface. The driver
69 supports hard disks and CD-ROMs, which have 512-byte sectors, or can
70 be switched to that mode. Due to the ACSI command format, only disks
71 up to 1 GB are supported. Special support for certain ACSI to SCSI
72 adapters, which could relax that, isn't included yet. The ACSI
73 driver is also the basis for certain other drivers for devices
74 attached to the ACSI bus: Atari SLM laser printer, BioNet-100
75 Ethernet, and PAMsNet Ethernet. If you want to use one of these
76 devices, you need ACSI support, too.
78 To compile this driver as a module, choose M here: the
79 module will be called acsi.
81 comment "Some devices (e.g. CD jukebox) support multiple LUNs"
82 depends on ATARI && ATARI_ACSI
84 config ACSI_MULTI_LUN
85 bool "Probe all LUNs on each ACSI device"
86 depends on ATARI_ACSI
87 help
88 If you have a ACSI device that supports more than one LUN (Logical
89 Unit Number), e.g. a CD jukebox, you should say Y here so that all
90 will be found by the ACSI driver. An ACSI device with multiple LUNs
91 acts logically like multiple ACSI devices. The vast majority of ACSI
92 devices have only one LUN, and so most people can say N here and
93 should in fact do so, because it is safer.
95 config ATARI_SLM
96 tristate "Atari SLM laser printer support"
97 depends on ATARI && ATARI_ACSI!=n
98 help
99 If you have an Atari SLM laser printer, say Y to include support for
100 it in the kernel. Otherwise, say N. This driver is also available as
101 a module ( = code which can be inserted in and removed from the
102 running kernel whenever you want). The module will be called
103 acsi_slm. Be warned: the driver needs much ST-RAM and can cause
104 problems due to that fact!
106 config BLK_DEV_XD
107 tristate "XT hard disk support"
108 depends on ISA && ISA_DMA_API
109 help
110 Very old 8 bit hard disk controllers used in the IBM XT computer
111 will be supported if you say Y here.
113 To compile this driver as a module, choose M here: the
114 module will be called xd.
116 It's pretty unlikely that you have one of these: say N.
118 config PARIDE
119 tristate "Parallel port IDE device support"
120 depends on PARPORT_PC
121 ---help---
122 There are many external CD-ROM and disk devices that connect through
123 your computer's parallel port. Most of them are actually IDE devices
124 using a parallel port IDE adapter. This option enables the PARIDE
125 subsystem which contains drivers for many of these external drives.
126 Read <file:Documentation/paride.txt> for more information.
128 If you have said Y to the "Parallel-port support" configuration
129 option, you may share a single port between your printer and other
130 parallel port devices. Answer Y to build PARIDE support into your
131 kernel, or M if you would like to build it as a loadable module. If
132 your parallel port support is in a loadable module, you must build
133 PARIDE as a module. If you built PARIDE support into your kernel,
134 you may still build the individual protocol modules and high-level
135 drivers as loadable modules. If you build this support as a module,
136 it will be called paride.
138 To use the PARIDE support, you must say Y or M here and also to at
139 least one high-level driver (e.g. "Parallel port IDE disks",
140 "Parallel port ATAPI CD-ROMs", "Parallel port ATAPI disks" etc.) and
141 to at least one protocol driver (e.g. "ATEN EH-100 protocol",
142 "MicroSolutions backpack protocol", "DataStor Commuter protocol"
143 etc.).
145 source "drivers/block/paride/Kconfig"
147 config BLK_CPQ_DA
148 tristate "Compaq SMART2 support"
149 depends on PCI
150 help
151 This is the driver for Compaq Smart Array controllers. Everyone
152 using these boards should say Y here. See the file
153 <file:Documentation/cpqarray.txt> for the current list of boards
154 supported by this driver, and for further information on the use of
155 this driver.
157 config BLK_CPQ_CISS_DA
158 tristate "Compaq Smart Array 5xxx support"
159 depends on PCI
160 help
161 This is the driver for Compaq Smart Array 5xxx controllers.
162 Everyone using these boards should say Y here.
163 See <file:Documentation/cciss.txt> for the current list of
164 boards supported by this driver, and for further information
165 on the use of this driver.
167 config CISS_SCSI_TAPE
168 bool "SCSI tape drive support for Smart Array 5xxx"
169 depends on BLK_CPQ_CISS_DA && SCSI && PROC_FS
170 help
171 When enabled (Y), this option allows SCSI tape drives and SCSI medium
172 changers (tape robots) to be accessed via a Compaq 5xxx array
173 controller. (See <file:Documentation/cciss.txt> for more details.)
175 "SCSI support" and "SCSI tape support" must also be enabled for this
176 option to work.
178 When this option is disabled (N), the SCSI portion of the driver
179 is not compiled.
181 config BLK_DEV_DAC960
182 tristate "Mylex DAC960/DAC1100 PCI RAID Controller support"
183 depends on PCI
184 help
185 This driver adds support for the Mylex DAC960, AcceleRAID, and
186 eXtremeRAID PCI RAID controllers. See the file
187 <file:Documentation/README.DAC960> for further information about
188 this driver.
190 To compile this driver as a module, choose M here: the
191 module will be called DAC960.
193 config BLK_DEV_UMEM
194 tristate "Micro Memory MM5415 Battery Backed RAM support (EXPERIMENTAL)"
195 depends on PCI && EXPERIMENTAL
196 ---help---
197 Saying Y here will include support for the MM5415 family of
198 battery backed (Non-volatile) RAM cards.
199 <http://www.umem.com/>
201 The cards appear as block devices that can be partitioned into
202 as many as 15 partitions.
204 To compile this driver as a module, choose M here: the
205 module will be called umem.
207 The umem driver has not yet been allocated a MAJOR number, so
208 one is chosen dynamically. Use "devfs" or look in /proc/devices
209 for the device number
211 config BLK_DEV_UBD
212 bool "Virtual block device"
213 depends on UML
214 ---help---
215 The User-Mode Linux port includes a driver called UBD which will let
216 you access arbitrary files on the host computer as block devices.
217 Unless you know that you do not need such virtual block devices say
218 Y here.
220 config BLK_DEV_UBD_SYNC
221 bool "Always do synchronous disk IO for UBD"
222 depends on BLK_DEV_UBD
223 ---help---
224 Writes to the virtual block device are not immediately written to the
225 host's disk; this may cause problems if, for example, the User-Mode
226 Linux 'Virtual Machine' uses a journalling filesystem and the host
227 computer crashes.
229 Synchronous operation (i.e. always writing data to the host's disk
230 immediately) is configurable on a per-UBD basis by using a special
231 kernel command line option. Alternatively, you can say Y here to
232 turn on synchronous operation by default for all block devices.
234 If you're running a journalling file system (like reiserfs, for
235 example) in your virtual machine, you will want to say Y here. If
236 you care for the safety of the data in your virtual machine, Y is a
237 wise choice too. In all other cases (for example, if you're just
238 playing around with User-Mode Linux) you can choose N.
241 bool
242 default BLK_DEV_UBD
244 config MMAPPER
245 tristate "Example IO memory driver (BROKEN)"
246 depends on UML && BROKEN
247 ---help---
248 The User-Mode Linux port can provide support for IO Memory
249 emulation with this option. This allows a host file to be
250 specified as an I/O region on the kernel command line. That file
251 will be mapped into UML's kernel address space where a driver can
252 locate it and do whatever it wants with the memory, including
253 providing an interface to it for UML processes to use.
255 For more information, see
256 <http://user-mode-linux.sourceforge.net/iomem.html>.
258 If you'd like to be able to provide a simulated IO port space for
259 User-Mode Linux processes, say Y. If unsure, say N.
261 config BLK_DEV_LOOP
262 tristate "Loopback device support"
263 ---help---
264 Saying Y here will allow you to use a regular file as a block
265 device; you can then create a file system on that block device and
266 mount it just as you would mount other block devices such as hard
267 drive partitions, CD-ROM drives or floppy drives. The loop devices
268 are block special device files with major number 7 and typically
269 called /dev/loop0, /dev/loop1 etc.
271 This is useful if you want to check an ISO 9660 file system before
272 burning the CD, or if you want to use floppy images without first
273 writing them to floppy. Furthermore, some Linux distributions avoid
274 the need for a dedicated Linux partition by keeping their complete
275 root file system inside a DOS FAT file using this loop device
276 driver.
278 To use the loop device, you need the losetup utility, found in the
279 util-linux package, see
280 <ftp://ftp.kernel.org/pub/linux/utils/util-linux/>.
282 The loop device driver can also be used to "hide" a file system in
283 a disk partition, floppy, or regular file, either using encryption
284 (scrambling the data) or steganography (hiding the data in the low
285 bits of, say, a sound file). This is also safe if the file resides
286 on a remote file server.
288 There are several ways of encrypting disks. Some of these require
289 kernel patches. The vanilla kernel offers the cryptoloop option
290 and a Device Mapper target (which is superior, as it supports all
291 file systems). If you want to use the cryptoloop, say Y to both
292 LOOP and CRYPTOLOOP, and make sure you have a recent (version 2.12
293 or later) version of util-linux. Additionally, be aware that
294 the cryptoloop is not safe for storing journaled filesystems.
296 Note that this loop device has nothing to do with the loopback
297 device used for network connections from the machine to itself.
299 To compile this driver as a module, choose M here: the
300 module will be called loop.
302 Most users will answer N here.
305 tristate "Cryptoloop Support"
306 select CRYPTO
307 depends on BLK_DEV_LOOP
308 ---help---
309 Say Y here if you want to be able to use the ciphers that are
310 provided by the CryptoAPI as loop transformation. This might be
311 used as hard disk encryption.
313 WARNING: This device is not safe for journaled file systems like
314 ext3 or Reiserfs. Please use the Device Mapper crypto module
315 instead, which can be configured to be on-disk compatible with the
316 cryptoloop device.
318 config BLK_DEV_NBD
319 tristate "Network block device support"
320 depends on NET
321 ---help---
322 Saying Y here will allow your computer to be a client for network
323 block devices, i.e. it will be able to use block devices exported by
324 servers (mount file systems on them etc.). Communication between
325 client and server works over TCP/IP networking, but to the client
326 program this is hidden: it looks like a regular local file access to
327 a block device special file such as /dev/nd0.
329 Network block devices also allows you to run a block-device in
330 userland (making server and client physically the same computer,
331 communicating using the loopback network device).
333 Read <file:Documentation/nbd.txt> for more information, especially
334 about where to find the server code, which runs in user space and
335 does not need special kernel support.
337 Note that this has nothing to do with the network file systems NFS
338 or Coda; you can say N here even if you intend to use NFS or Coda.
340 To compile this driver as a module, choose M here: the
341 module will be called nbd.
343 If unsure, say N.
345 config BLK_DEV_SX8
346 tristate "Promise SATA SX8 support"
347 depends on PCI
348 ---help---
349 Saying Y or M here will enable support for the
350 Promise SATA SX8 controllers.
352 Use devices /dev/sx8/$N and /dev/sx8/$Np$M.
354 config BLK_DEV_UB
355 tristate "Low Performance USB Block driver"
356 depends on USB
357 help
358 This driver supports certain USB attached storage devices
359 such as flash keys.
361 If you enable this driver, it is recommended to avoid conflicts
362 with usb-storage by enabling USB_LIBUSUAL.
364 If unsure, say N.
366 config BLK_DEV_RAM
367 tristate "RAM disk support"
368 ---help---
369 Saying Y here will allow you to use a portion of your RAM memory as
370 a block device, so that you can make file systems on it, read and
371 write to it and do all the other things that you can do with normal
372 block devices (such as hard drives). It is usually used to load and
373 store a copy of a minimal root file system off of a floppy into RAM
374 during the initial install of Linux.
376 Note that the kernel command line option "ramdisk=XX" is now
377 obsolete. For details, read <file:Documentation/ramdisk.txt>.
379 To compile this driver as a module, choose M here: the
380 module will be called rd.
382 Most normal users won't need the RAM disk functionality, and can
383 thus say N here.
385 config BLK_DEV_RAM_COUNT
386 int "Default number of RAM disks"
387 default "16"
388 depends on BLK_DEV_RAM
389 help
390 The default value is 16 RAM disks. Change this if you know what
391 are doing. If you boot from a filesystem that needs to be extracted
392 in memory, you will need at least one RAM disk (e.g. root on cramfs).
394 config BLK_DEV_RAM_SIZE
395 int "Default RAM disk size (kbytes)"
396 depends on BLK_DEV_RAM
397 default "4096"
398 help
399 The default value is 4096 kilobytes. Only change this if you know
400 what are you doing. If you are using IBM S/390, then set this to
401 8192.
404 int "Default RAM disk block size (bytes)"
405 depends on BLK_DEV_RAM
406 default "1024"
407 help
408 The default value is 1024 kilobytes. PAGE_SIZE is a much more
409 efficient choice however. The default is kept to ensure initrd
410 setups function - apparently needed by the rd_load_image routine
411 that supposes the filesystem in the image uses a 1024 blocksize.
413 config BLK_DEV_INITRD
414 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
415 depends on BROKEN || !FRV
416 help
417 The initial RAM filesystem is a ramfs which is loaded by the
418 boot loader (loadlin or lilo) and that is mounted as root
419 before the normal boot procedure. It is typically used to
420 load modules needed to mount the "real" root file system,
421 etc. See <file:Documentation/initrd.txt> for details.
423 If RAM disk support (BLK_DEV_RAM) is also included, this
424 also enables initial RAM disk (initrd) support.
427 config CDROM_PKTCDVD
428 tristate "Packet writing on CD/DVD media"
429 depends on !UML
430 help
431 If you have a CDROM drive that supports packet writing, say Y to
432 include preliminary support. It should work with any MMC/Mt Fuji
433 compliant ATAPI or SCSI drive, which is just about any newer CD
434 writer.
436 Currently only writing to CD-RW, DVD-RW and DVD+RW discs is possible.
437 DVD-RW disks must be in restricted overwrite mode.
439 To compile this driver as a module, choose M here: the
440 module will be called pktcdvd.
443 int "Free buffers for data gathering"
444 depends on CDROM_PKTCDVD
445 default "8"
446 help
447 This controls the maximum number of active concurrent packets. More
448 concurrent packets can increase write performance, but also require
449 more memory. Each concurrent packet will require approximately 64Kb
450 of non-swappable kernel memory, memory which will be allocated when
451 a disc is opened for writing.
454 bool "Enable write caching (EXPERIMENTAL)"
456 help
457 If enabled, write caching will be set for the CD-R/W device. For now
458 this option is dangerous unless the CD-RW media is known good, as we
459 don't do deferred write error handling yet.
461 source "drivers/s390/block/Kconfig"
463 config ATA_OVER_ETH
464 tristate "ATA over Ethernet support"
465 depends on NET
466 help
467 This driver provides Support for ATA over Ethernet block
468 devices like the Coraid EtherDrive (R) Storage Blade.
470 endmenu