ia64/linux-2.6.18-xen.hg

view Documentation/ioctl-number.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
children
line source
1 Ioctl Numbers
2 19 October 1999
3 Michael Elizabeth Chastain
4 <mec@shout.net>
6 If you are adding new ioctl's to the kernel, you should use the _IO
7 macros defined in <linux/ioctl.h>:
9 _IO an ioctl with no parameters
10 _IOW an ioctl with write parameters (copy_from_user)
11 _IOR an ioctl with read parameters (copy_to_user)
12 _IOWR an ioctl with both write and read parameters.
14 'Write' and 'read' are from the user's point of view, just like the
15 system calls 'write' and 'read'. For example, a SET_FOO ioctl would
16 be _IOW, although the kernel would actually read data from user space;
17 a GET_FOO ioctl would be _IOR, although the kernel would actually write
18 data to user space.
20 The first argument to _IO, _IOW, _IOR, or _IOWR is an identifying letter
21 or number from the table below. Because of the large number of drivers,
22 many drivers share a partial letter with other drivers.
24 If you are writing a driver for a new device and need a letter, pick an
25 unused block with enough room for expansion: 32 to 256 ioctl commands.
26 You can register the block by patching this file and submitting the
27 patch to Linus Torvalds. Or you can e-mail me at <mec@shout.net> and
28 I'll register one for you.
30 The second argument to _IO, _IOW, _IOR, or _IOWR is a sequence number
31 to distinguish ioctls from each other. The third argument to _IOW,
32 _IOR, or _IOWR is the type of the data going into the kernel or coming
33 out of the kernel (e.g. 'int' or 'struct foo'). NOTE! Do NOT use
34 sizeof(arg) as the third argument as this results in your ioctl thinking
35 it passes an argument of type size_t.
37 Some devices use their major number as the identifier; this is OK, as
38 long as it is unique. Some devices are irregular and don't follow any
39 convention at all.
41 Following this convention is good because:
43 (1) Keeping the ioctl's globally unique helps error checking:
44 if a program calls an ioctl on the wrong device, it will get an
45 error rather than some unexpected behaviour.
47 (2) The 'strace' build procedure automatically finds ioctl numbers
48 defined with _IO, _IOW, _IOR, or _IOWR.
50 (3) 'strace' can decode numbers back into useful names when the
51 numbers are unique.
53 (4) People looking for ioctls can grep for them more easily when
54 this convention is used to define the ioctl numbers.
56 (5) When following the convention, the driver code can use generic
57 code to copy the parameters between user and kernel space.
59 This table lists ioctls visible from user land for Linux/i386. It contains
60 most drivers up to 2.3.14, but I know I am missing some.
62 Code Seq# Include File Comments
63 ========================================================
64 0x00 00-1F linux/fs.h conflict!
65 0x00 00-1F scsi/scsi_ioctl.h conflict!
66 0x00 00-1F linux/fb.h conflict!
67 0x00 00-1F linux/wavefront.h conflict!
68 0x02 all linux/fd.h
69 0x03 all linux/hdreg.h
70 0x04 all linux/umsdos_fs.h
71 0x06 all linux/lp.h
72 0x09 all linux/md.h
73 0x12 all linux/fs.h
74 linux/blkpg.h
75 0x1b all InfiniBand Subsystem <http://www.openib.org/>
76 0x20 all drivers/cdrom/cm206.h
77 0x22 all scsi/sg.h
78 '#' 00-3F IEEE 1394 Subsystem Block for the entire subsystem
79 '1' 00-1F <linux/timepps.h> PPS kit from Ulrich Windl
80 <ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/>
81 '8' all SNP8023 advanced NIC card
82 <mailto:mcr@solidum.com>
83 'A' 00-1F linux/apm_bios.h
84 'B' C0-FF advanced bbus
85 <mailto:maassen@uni-freiburg.de>
86 'C' all linux/soundcard.h
87 'D' all asm-s390/dasd.h
88 'E' all linux/input.h
89 'F' all linux/fb.h
90 'H' all linux/hiddev.h
91 'I' all linux/isdn.h
92 'J' 00-1F drivers/scsi/gdth_ioctl.h
93 'K' all linux/kd.h
94 'L' 00-1F linux/loop.h
95 'L' E0-FF linux/ppdd.h encrypted disk device driver
96 <http://linux01.gwdg.de/~alatham/ppdd.html>
97 'M' all linux/soundcard.h conflict!
98 'M' 00-1F linux/isicom.h conflict!
99 'N' 00-1F drivers/usb/scanner.h
100 'P' all linux/soundcard.h
101 'Q' all linux/soundcard.h
102 'R' 00-1F linux/random.h
103 'S' all linux/cdrom.h conflict!
104 'S' 80-81 scsi/scsi_ioctl.h conflict!
105 'S' 82-FF scsi/scsi.h conflict!
106 'T' all linux/soundcard.h conflict!
107 'T' all asm-i386/ioctls.h conflict!
108 'U' 00-EF linux/drivers/usb/usb.h
109 'U' F0-FF drivers/usb/auerswald.c
110 'V' all linux/vt.h
111 'W' 00-1F linux/watchdog.h conflict!
112 'W' 00-1F linux/wanrouter.h conflict!
113 'X' all linux/xfs_fs.h
114 'Y' all linux/cyclades.h
115 'a' all ATM on linux
116 <http://lrcwww.epfl.ch/linux-atm/magic.html>
117 'b' 00-FF bit3 vme host bridge
118 <mailto:natalia@nikhefk.nikhef.nl>
119 'c' 00-7F linux/comstats.h conflict!
120 'c' 00-7F linux/coda.h conflict!
121 'd' 00-FF linux/char/drm/drm/h conflict!
122 'd' 00-DF linux/video_decoder.h conflict!
123 'd' F0-FF linux/digi1.h
124 'e' all linux/digi1.h conflict!
125 'e' 00-1F linux/video_encoder.h conflict!
126 'e' 00-1F net/irda/irtty.h conflict!
127 'f' 00-1F linux/ext2_fs.h
128 'h' 00-7F Charon filesystem
129 <mailto:zapman@interlan.net>
130 'i' 00-3F linux/i2o.h
131 'j' 00-3F linux/joystick.h
132 'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system
133 <http://mikonos.dia.unisa.it/tcfs>
134 'l' 40-7F linux/udf_fs_i.h in development:
135 <http://sourceforge.net/projects/linux-udf/>
136 'm' all linux/mtio.h conflict!
137 'm' all linux/soundcard.h conflict!
138 'm' all linux/synclink.h conflict!
139 'm' 00-1F net/irda/irmod.h conflict!
140 'n' 00-7F linux/ncp_fs.h
141 'n' E0-FF video/matrox.h matroxfb
142 'p' 00-3F linux/mc146818rtc.h
143 'p' 40-7F linux/nvram.h
144 'p' 80-9F user-space parport
145 <mailto:tim@cyberelk.net>
146 'q' 00-1F linux/serio.h
147 'q' 80-FF Internet PhoneJACK, Internet LineJACK
148 <http://www.quicknet.net>
149 'r' 00-1F linux/msdos_fs.h
150 's' all linux/cdk.h
151 't' 00-7F linux/if_ppp.h
152 't' 80-8F linux/isdn_ppp.h
153 'u' 00-1F linux/smb_fs.h
154 'v' 00-1F linux/ext2_fs.h conflict!
155 'v' all linux/videodev.h conflict!
156 'w' all CERN SCI driver
157 'y' 00-1F packet based user level communications
158 <mailto:zapman@interlan.net>
159 'z' 00-3F CAN bus card
160 <mailto:hdstich@connectu.ulm.circular.de>
161 'z' 40-7F CAN bus card
162 <mailto:oe@port.de>
163 0x80 00-1F linux/fb.h
164 0x81 00-1F linux/videotext.h
165 0x89 00-06 asm-i386/sockios.h
166 0x89 0B-DF linux/sockios.h
167 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
168 0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range
169 0x8B all linux/wireless.h
170 0x8C 00-3F WiNRADiO driver
171 <http://www.proximity.com.au/~brian/winradio/>
172 0x90 00 drivers/cdrom/sbpcd.h
173 0x93 60-7F linux/auto_fs.h
174 0x99 00-0F 537-Addinboard driver
175 <mailto:buk@buks.ipn.de>
176 0xA0 all linux/sdp/sdp.h Industrial Device Project
177 <mailto:kenji@bitgate.com>
178 0xA3 80-8F Port ACL in development:
179 <mailto:tlewis@mindspring.com>
180 0xA3 90-9F linux/dtlk.h
181 0xAB 00-1F linux/nbd.h
182 0xAC 00-1F linux/raw.h
183 0xAD 00 Netfilter device in development:
184 <mailto:rusty@rustcorp.com.au>
185 0xB0 all RATIO devices in development:
186 <mailto:vgo@ratio.de>
187 0xB1 00-1F PPPoX <mailto:mostrows@styx.uwaterloo.ca>
188 0xCB 00-1F CBM serial IEC bus in development:
189 <mailto:michael.klein@puffin.lb.shuttle.de>
190 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/
191 <mailto:aherrman@de.ibm.com>
192 0xF3 00-3F video/sisfb.h sisfb (in development)
193 <mailto:thomas@winischhofer.net>