ia64/linux-2.6.18-xen.hg

view Documentation/usb/proc_usb_info.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 /proc/bus/usb filesystem output
2 ===============================
3 (version 2003.05.30)
6 The usbfs filesystem for USB devices is traditionally mounted at
7 /proc/bus/usb. It provides the /proc/bus/usb/devices file, as well as
8 the /proc/bus/usb/BBB/DDD files.
11 **NOTE**: If /proc/bus/usb appears empty, and a host controller
12 driver has been linked, then you need to mount the
13 filesystem. Issue the command (as root):
15 mount -t usbfs none /proc/bus/usb
17 An alternative and more permanent method would be to add
19 none /proc/bus/usb usbfs defaults 0 0
21 to /etc/fstab. This will mount usbfs at each reboot.
22 You can then issue `cat /proc/bus/usb/devices` to extract
23 USB device information, and user mode drivers can use usbfs
24 to interact with USB devices.
26 There are a number of mount options supported by usbfs.
27 Consult the source code (linux/drivers/usb/core/inode.c) for
28 information about those options.
30 **NOTE**: The filesystem has been renamed from "usbdevfs" to
31 "usbfs", to reduce confusion with "devfs". You may
32 still see references to the older "usbdevfs" name.
34 For more information on mounting the usbfs file system, see the
35 "USB Device Filesystem" section of the USB Guide. The latest copy
36 of the USB Guide can be found at http://www.linux-usb.org/
39 THE /proc/bus/usb/BBB/DDD FILES:
40 --------------------------------
41 Each connected USB device has one file. The BBB indicates the bus
42 number. The DDD indicates the device address on that bus. Both
43 of these numbers are assigned sequentially, and can be reused, so
44 you can't rely on them for stable access to devices. For example,
45 it's relatively common for devices to re-enumerate while they are
46 still connected (perhaps someone jostled their power supply, hub,
47 or USB cable), so a device might be 002/027 when you first connect
48 it and 002/048 sometime later.
50 These files can be read as binary data. The binary data consists
51 of first the device descriptor, then the descriptors for each
52 configuration of the device. That information is also shown in
53 text form by the /proc/bus/usb/devices file, described later.
55 These files may also be used to write user-level drivers for the USB
56 devices. You would open the /proc/bus/usb/BBB/DDD file read/write,
57 read its descriptors to make sure it's the device you expect, and then
58 bind to an interface (or perhaps several) using an ioctl call. You
59 would issue more ioctls to the device to communicate to it using
60 control, bulk, or other kinds of USB transfers. The IOCTLs are
61 listed in the <linux/usbdevice_fs.h> file, and at this writing the
62 source code (linux/drivers/usb/core/devio.c) is the primary reference
63 for how to access devices through those files.
65 Note that since by default these BBB/DDD files are writable only by
66 root, only root can write such user mode drivers. You can selectively
67 grant read/write permissions to other users by using "chmod". Also,
68 usbfs mount options such as "devmode=0666" may be helpful.
72 THE /proc/bus/usb/devices FILE:
73 -------------------------------
74 In /proc/bus/usb/devices, each device's output has multiple
75 lines of ASCII output.
76 I made it ASCII instead of binary on purpose, so that someone
77 can obtain some useful data from it without the use of an
78 auxiliary program. However, with an auxiliary program, the numbers
79 in the first 4 columns of each "T:" line (topology info:
80 Lev, Prnt, Port, Cnt) can be used to build a USB topology diagram.
82 Each line is tagged with a one-character ID for that line:
84 T = Topology (etc.)
85 B = Bandwidth (applies only to USB host controllers, which are
86 virtualized as root hubs)
87 D = Device descriptor info.
88 P = Product ID info. (from Device descriptor, but they won't fit
89 together on one line)
90 S = String descriptors.
91 C = Configuration descriptor info. (* = active configuration)
92 I = Interface descriptor info.
93 E = Endpoint descriptor info.
95 =======================================================================
97 /proc/bus/usb/devices output format:
99 Legend:
100 d = decimal number (may have leading spaces or 0's)
101 x = hexadecimal number (may have leading spaces or 0's)
102 s = string
105 Topology info:
107 T: Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd
108 | | | | | | | | |__MaxChildren
109 | | | | | | | |__Device Speed in Mbps
110 | | | | | | |__DeviceNumber
111 | | | | | |__Count of devices at this level
112 | | | | |__Connector/Port on Parent for this device
113 | | | |__Parent DeviceNumber
114 | | |__Level in topology for this bus
115 | |__Bus number
116 |__Topology info tag
118 Speed may be:
119 1.5 Mbit/s for low speed USB
120 12 Mbit/s for full speed USB
121 480 Mbit/s for high speed USB (added for USB 2.0)
124 Bandwidth info:
125 B: Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd
126 | | | |__Number of isochronous requests
127 | | |__Number of interrupt requests
128 | |__Total Bandwidth allocated to this bus
129 |__Bandwidth info tag
131 Bandwidth allocation is an approximation of how much of one frame
132 (millisecond) is in use. It reflects only periodic transfers, which
133 are the only transfers that reserve bandwidth. Control and bulk
134 transfers use all other bandwidth, including reserved bandwidth that
135 is not used for transfers (such as for short packets).
137 The percentage is how much of the "reserved" bandwidth is scheduled by
138 those transfers. For a low or full speed bus (loosely, "USB 1.1"),
139 90% of the bus bandwidth is reserved. For a high speed bus (loosely,
140 "USB 2.0") 80% is reserved.
143 Device descriptor info & Product ID info:
145 D: Ver=x.xx Cls=xx(s) Sub=xx Prot=xx MxPS=dd #Cfgs=dd
146 P: Vendor=xxxx ProdID=xxxx Rev=xx.xx
148 where
149 D: Ver=x.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd
150 | | | | | | |__NumberConfigurations
151 | | | | | |__MaxPacketSize of Default Endpoint
152 | | | | |__DeviceProtocol
153 | | | |__DeviceSubClass
154 | | |__DeviceClass
155 | |__Device USB version
156 |__Device info tag #1
158 where
159 P: Vendor=xxxx ProdID=xxxx Rev=xx.xx
160 | | | |__Product revision number
161 | | |__Product ID code
162 | |__Vendor ID code
163 |__Device info tag #2
166 String descriptor info:
168 S: Manufacturer=ssss
169 | |__Manufacturer of this device as read from the device.
170 | For USB host controller drivers (virtual root hubs) this may
171 | be omitted, or (for newer drivers) will identify the kernel
172 | version and the driver which provides this hub emulation.
173 |__String info tag
175 S: Product=ssss
176 | |__Product description of this device as read from the device.
177 | For older USB host controller drivers (virtual root hubs) this
178 | indicates the driver; for newer ones, it's a product (and vendor)
179 | description that often comes from the kernel's PCI ID database.
180 |__String info tag
182 S: SerialNumber=ssss
183 | |__Serial Number of this device as read from the device.
184 | For USB host controller drivers (virtual root hubs) this is
185 | some unique ID, normally a bus ID (address or slot name) that
186 | can't be shared with any other device.
187 |__String info tag
191 Configuration descriptor info:
193 C:* #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA
194 | | | | | |__MaxPower in mA
195 | | | | |__Attributes
196 | | | |__ConfiguratioNumber
197 | | |__NumberOfInterfaces
198 | |__ "*" indicates the active configuration (others are " ")
199 |__Config info tag
201 USB devices may have multiple configurations, each of which act
202 rather differently. For example, a bus-powered configuration
203 might be much less capable than one that is self-powered. Only
204 one device configuration can be active at a time; most devices
205 have only one configuration.
207 Each configuration consists of one or more interfaces. Each
208 interface serves a distinct "function", which is typically bound
209 to a different USB device driver. One common example is a USB
210 speaker with an audio interface for playback, and a HID interface
211 for use with software volume control.
214 Interface descriptor info (can be multiple per Config):
216 I: If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=ssss
217 | | | | | | | |__Driver name
218 | | | | | | | or "(none)"
219 | | | | | | |__InterfaceProtocol
220 | | | | | |__InterfaceSubClass
221 | | | | |__InterfaceClass
222 | | | |__NumberOfEndpoints
223 | | |__AlternateSettingNumber
224 | |__InterfaceNumber
225 |__Interface info tag
227 A given interface may have one or more "alternate" settings.
228 For example, default settings may not use more than a small
229 amount of periodic bandwidth. To use significant fractions
230 of bus bandwidth, drivers must select a non-default altsetting.
232 Only one setting for an interface may be active at a time, and
233 only one driver may bind to an interface at a time. Most devices
234 have only one alternate setting per interface.
237 Endpoint descriptor info (can be multiple per Interface):
239 E: Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=dddss
240 | | | | |__Interval (max) between transfers
241 | | | |__EndpointMaxPacketSize
242 | | |__Attributes(EndpointType)
243 | |__EndpointAddress(I=In,O=Out)
244 |__Endpoint info tag
246 The interval is nonzero for all periodic (interrupt or isochronous)
247 endpoints. For high speed endpoints the transfer interval may be
248 measured in microseconds rather than milliseconds.
250 For high speed periodic endpoints, the "MaxPacketSize" reflects
251 the per-microframe data transfer size. For "high bandwidth"
252 endpoints, that can reflect two or three packets (for up to
253 3KBytes every 125 usec) per endpoint.
255 With the Linux-USB stack, periodic bandwidth reservations use the
256 transfer intervals and sizes provided by URBs, which can be less
257 than those found in endpoint descriptor.
260 =======================================================================
263 If a user or script is interested only in Topology info, for
264 example, use something like "grep ^T: /proc/bus/usb/devices"
265 for only the Topology lines. A command like
266 "grep -i ^[tdp]: /proc/bus/usb/devices" can be used to list
267 only the lines that begin with the characters in square brackets,
268 where the valid characters are TDPCIE. With a slightly more able
269 script, it can display any selected lines (for example, only T, D,
270 and P lines) and change their output format. (The "procusb"
271 Perl script is the beginning of this idea. It will list only
272 selected lines [selected from TBDPSCIE] or "All" lines from
273 /proc/bus/usb/devices.)
275 The Topology lines can be used to generate a graphic/pictorial
276 of the USB devices on a system's root hub. (See more below
277 on how to do this.)
279 The Interface lines can be used to determine what driver is
280 being used for each device.
282 The Configuration lines could be used to list maximum power
283 (in milliamps) that a system's USB devices are using.
284 For example, "grep ^C: /proc/bus/usb/devices".
287 Here's an example, from a system which has a UHCI root hub,
288 an external hub connected to the root hub, and a mouse and
289 a serial converter connected to the external hub.
291 T: Bus=00 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
292 B: Alloc= 28/900 us ( 3%), #Int= 2, #Iso= 0
293 D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
294 P: Vendor=0000 ProdID=0000 Rev= 0.00
295 S: Product=USB UHCI Root Hub
296 S: SerialNumber=dce0
297 C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr= 0mA
298 I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
299 E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl=255ms
301 T: Bus=00 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 4
302 D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
303 P: Vendor=0451 ProdID=1446 Rev= 1.00
304 C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
305 I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
306 E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=255ms
308 T: Bus=00 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=1.5 MxCh= 0
309 D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
310 P: Vendor=04b4 ProdID=0001 Rev= 0.00
311 C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
312 I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=02 Driver=mouse
313 E: Ad=81(I) Atr=03(Int.) MxPS= 3 Ivl= 10ms
315 T: Bus=00 Lev=02 Prnt=02 Port=02 Cnt=02 Dev#= 4 Spd=12 MxCh= 0
316 D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
317 P: Vendor=0565 ProdID=0001 Rev= 1.08
318 S: Manufacturer=Peracom Networks, Inc.
319 S: Product=Peracom USB to Serial Converter
320 C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
321 I: If#= 0 Alt= 0 #EPs= 3 Cls=00(>ifc ) Sub=00 Prot=00 Driver=serial
322 E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl= 16ms
323 E: Ad=01(O) Atr=02(Bulk) MxPS= 16 Ivl= 16ms
324 E: Ad=82(I) Atr=03(Int.) MxPS= 8 Ivl= 8ms
327 Selecting only the "T:" and "I:" lines from this (for example, by using
328 "procusb ti"), we have:
330 T: Bus=00 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
331 T: Bus=00 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 4
332 I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
333 T: Bus=00 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=1.5 MxCh= 0
334 I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=02 Driver=mouse
335 T: Bus=00 Lev=02 Prnt=02 Port=02 Cnt=02 Dev#= 4 Spd=12 MxCh= 0
336 I: If#= 0 Alt= 0 #EPs= 3 Cls=00(>ifc ) Sub=00 Prot=00 Driver=serial
339 Physically this looks like (or could be converted to):
341 +------------------+
342 | PC/root_hub (12)| Dev# = 1
343 +------------------+ (nn) is Mbps.
344 Level 0 | CN.0 | CN.1 | [CN = connector/port #]
345 +------------------+
346 /
347 /
348 +-----------------------+
349 Level 1 | Dev#2: 4-port hub (12)|
350 +-----------------------+
351 |CN.0 |CN.1 |CN.2 |CN.3 |
352 +-----------------------+
353 \ \____________________
354 \_____ \
355 \ \
356 +--------------------+ +--------------------+
357 Level 2 | Dev# 3: mouse (1.5)| | Dev# 4: serial (12)|
358 +--------------------+ +--------------------+
362 Or, in a more tree-like structure (ports [Connectors] without
363 connections could be omitted):
365 PC: Dev# 1, root hub, 2 ports, 12 Mbps
366 |_ CN.0: Dev# 2, hub, 4 ports, 12 Mbps
367 |_ CN.0: Dev #3, mouse, 1.5 Mbps
368 |_ CN.1:
369 |_ CN.2: Dev #4, serial, 12 Mbps
370 |_ CN.3:
371 |_ CN.1:
374 ### END ###