proc.txt

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

Linux uses  slab  pools for memory management above page level in version 2.2.
Commonly used  objects  have  their  own  slab  pool (such as network buffers,
directory cache, and so on).

1.3 IDE devices in /proc/ide
----------------------------

The subdirectory /proc/ide contains information about all IDE devices of which
the kernel  is  aware.  There is one subdirectory for each IDE controller, the
file drivers  and a link for each IDE device, pointing to the device directory
in the controller specific subtree.

The file  drivers  contains general information about the drivers used for the
IDE devices:

  > cat /proc/ide/drivers 
  ide-cdrom version 4.53 
  ide-disk version 1.08 


More detailed  information  can  be  found  in  the  controller  specific
subdirectories. These  are  named  ide0,  ide1  and  so  on.  Each  of  these
directories contains the files shown in table 1-4.


Table 1-4: IDE controller info in  /proc/ide/ide? 
..............................................................................
 File    Content                                 
 channel IDE channel (0 or 1)                    
 config  Configuration (only for PCI/IDE bridge) 
 mate    Mate name                               
 model   Type/Chipset of IDE controller          
..............................................................................

Each device  connected  to  a  controller  has  a separate subdirectory in the
controllers directory.  The  files  listed in table 1-5 are contained in these
directories.


Table 1-5: IDE device information 
..............................................................................
 File             Content                                    
 cache            The cache                                  
 capacity         Capacity of the medium (in 512Byte blocks) 
 driver           driver and version                         
 geometry         physical and logical geometry              
 identify         device identify block                      
 media            media type                                 
 model            device identifier                          
 settings         device setup                               
 smart_thresholds IDE disk management thresholds             
 smart_values     IDE disk management values                 
..............................................................................

The most  interesting  file is settings. This file contains a nice overview of
the drive parameters:

  # cat /proc/ide/ide0/hda/settings 
  name                    value           min             max             mode 
  ----                    -----           ---             ---             ---- 
  bios_cyl                526             0               65535           rw 
  bios_head               255             0               255             rw 
  bios_sect               63              0               63              rw 
  breada_readahead        4               0               127             rw 
  bswap                   0               0               1               r 
  file_readahead          72              0               2097151         rw 
  io_32bit                0               0               3               rw 
  keepsettings            0               0               1               rw 
  max_kb_per_request      122             1               127             rw 
  multcount               0               0               8               rw 
  nice1                   1               0               1               rw 
  nowerr                  0               0               1               rw 
  pio_mode                write-only      0               255             w 
  slow                    0               0               1               rw 
  unmaskirq               0               0               1               rw 
  using_dma               0               0               1               rw 


1.4 Networking info in /proc/net
--------------------------------

The subdirectory  /proc/net  follows  the  usual  pattern. Table 1-6 shows the
additional values  you  get  for  IP  version 6 if you configure the kernel to
support this. Table 1-7 lists the files and their meaning.


Table 1-6: IPv6 info in /proc/net 
..............................................................................
 File       Content                                               
 udp6       UDP sockets (IPv6)                                    
 tcp6       TCP sockets (IPv6)                                    
 raw6       Raw device statistics (IPv6)                          
 igmp6      IP multicast addresses, which this host joined (IPv6) 
 if_inet6   List of IPv6 interface addresses                      
 ipv6_route Kernel routing table for IPv6                         
 rt6_stats  Global IPv6 routing tables statistics                 
 sockstat6  Socket statistics (IPv6)                              
 snmp6      Snmp data (IPv6)                                      
..............................................................................


Table 1-7: Network info in /proc/net 
..............................................................................
 File          Content                                                         
 arp           Kernel  ARP table                                               
 dev           network devices with statistics                                 
 dev_mcast     the Layer2 multicast groups a device is listening too
               (interface index, label, number of references, number of bound
               addresses). 
 dev_stat      network device status                                           
 ip_fwchains   Firewall chain linkage                                          
 ip_fwnames    Firewall chain names                                            
 ip_masq       Directory containing the masquerading tables                    
 ip_masquerade Major masquerading table                                        
 netstat       Network statistics                                              
 raw           raw device statistics                                           
 route         Kernel routing table                                            
 rpc           Directory containing rpc info                                   
 rt_cache      Routing cache                                                   
 snmp          SNMP data                                                       
 sockstat      Socket statistics                                               
 tcp           TCP  sockets                                                    
 tr_rif        Token ring RIF routing table                                    
 udp           UDP sockets                                                     
 unix          UNIX domain sockets                                             
 wireless      Wireless interface data (Wavelan etc)                           
 igmp          IP multicast addresses, which this host joined                  
 psched        Global packet scheduler parameters.                             
 netlink       List of PF_NETLINK sockets                                      
 ip_mr_vifs    List of multicast virtual interfaces                            
 ip_mr_cache   List of multicast routing cache                                 
..............................................................................

You can  use  this  information  to see which network devices are available in
your system and how much traffic was routed over those devices:

  > cat /proc/net/dev 
  Inter-|Receive                                                   |[... 
   face |bytes    packets errs drop fifo frame compressed multicast|[... 
      lo:  908188   5596     0    0    0     0          0         0 [...         
    ppp0:15475140  20721   410    0    0   410          0         0 [...  
    eth0:  614530   7085     0    0    0     0          0         1 [... 
   
  ...] Transmit 
  ...] bytes    packets errs drop fifo colls carrier compressed 
  ...]  908188     5596    0    0    0     0       0          0 
  ...] 1375103    17405    0    0    0     0       0          0 
  ...] 1703981     5535    0    0    0     3       0          0 

In addition, each Channel Bond interface has it's own directory.  For
example, the bond0 device will have a directory called /proc/net/bond0/.
It will contain information that is specific to that bond, such as the
current slaves of the bond, the link status of the slaves, and how
many times the slaves link has failed.

1.5 SCSI info
-------------

If you  have  a  SCSI  host adapter in your system, you'll find a subdirectory
named after  the driver for this adapter in /proc/scsi. You'll also see a list
of all recognized SCSI devices in /proc/scsi:

  >cat /proc/scsi/scsi 
  Attached devices: 
  Host: scsi0 Channel: 00 Id: 00 Lun: 00 
    Vendor: IBM      Model: DGHS09U          Rev: 03E0 
    Type:   Direct-Access                    ANSI SCSI revision: 03 
  Host: scsi0 Channel: 00 Id: 06 Lun: 00 
    Vendor: PIONEER  Model: CD-ROM DR-U06S   Rev: 1.04 
    Type:   CD-ROM                           ANSI SCSI revision: 02 


The directory  named  after  the driver has one file for each adapter found in
the system.  These  files  contain information about the controller, including
the used  IRQ  and  the  IO  address range. The amount of information shown is
dependent on  the adapter you use. The example shows the output for an Adaptec
AHA-2940 SCSI adapter:

  > cat /proc/scsi/aic7xxx/0 
   
  Adaptec AIC7xxx driver version: 5.1.19/3.2.4 
  Compile Options: 
    TCQ Enabled By Default : Disabled 
    AIC7XXX_PROC_STATS     : Disabled 
    AIC7XXX_RESET_DELAY    : 5 
  Adapter Configuration: 
             SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter 
                             Ultra Wide Controller 
      PCI MMAPed I/O Base: 0xeb001000 
   Adapter SEEPROM Config: SEEPROM found and used. 
        Adaptec SCSI BIOS: Enabled 
                      IRQ: 10 
                     SCBs: Active 0, Max Active 2, 
                           Allocated 15, HW 16, Page 255 
               Interrupts: 160328 
        BIOS Control Word: 0x18b6 
     Adapter Control Word: 0x005b 
     Extended Translation: Enabled 
  Disconnect Enable Flags: 0xffff 
       Ultra Enable Flags: 0x0001 
   Tag Queue Enable Flags: 0x0000 
  Ordered Queue Tag Flags: 0x0000 
  Default Tag Queue Depth: 8 
      Tagged Queue By Device array for aic7xxx host instance 0: 
        {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255} 
      Actual queue depth per device for aic7xxx host instance 0: 
        {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1} 
  Statistics: 
  (scsi0:0:0:0) 
    Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8 
    Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0) 
    Total transfers 160151 (74577 reads and 85574 writes) 
  (scsi0:0:6:0) 
    Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15 
    Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0) 
    Total transfers 0 (0 reads and 0 writes) 


1.6 Parallel port info in /proc/parport
---------------------------------------

The directory  /proc/parport  contains information about the parallel ports of
your system.  It  has  one  subdirectory  for  each port, named after the port
number (0,1,2,...).

These directories contain the four files shown in Table 1-8.


Table 1-8: Files in /proc/parport 
..............................................................................
 File      Content                                                             
 autoprobe Any IEEE-1284 device ID information that has been acquired.         
 devices   list of the device drivers using that port. A + will appear by the
           name of the device currently using the port (it might not appear
           against any). 
 hardware  Parallel port's base address, IRQ line and DMA channel.             
 irq       IRQ that parport is using for that port. This is in a separate
           file to allow you to alter it by writing a new value in (IRQ
           number or none). 
..............................................................................

1.7 TTY info in /proc/tty
-------------------------

Information about  the  available  and actually used tty's can be found in the
directory /proc/tty.You'll  find  entries  for drivers and line disciplines in
this directory, as shown in Table 1-9.


Table 1-9: Files in /proc/tty 
..............................................................................
 File          Content                                        
 drivers       list of drivers and their usage                
 ldiscs        registered line disciplines                    
 driver/serial usage statistic and status of single tty lines 
..............................................................................

To see  which  tty's  are  currently in use, you can simply look into the file
/proc/tty/drivers:

  > cat /proc/tty/drivers 
  pty_slave            /dev/pts      136   0-255 pty:slave 
  pty_master           /dev/ptm      128   0-255 pty:master 
  pty_slave            /dev/ttyp       3   0-255 pty:slave 
  pty_master           /dev/pty        2   0-255 pty:master 
  serial               /dev/cua        5   64-67 serial:callout 
  serial               /dev/ttyS       4   64-67 serial 
  /dev/tty0            /dev/tty0       4       0 system:vtmaster 
  /dev/ptmx            /dev/ptmx       5       2 system 
  /dev/console         /dev/console    5       1 system:console 
  /dev/tty             /dev/tty        5       0 system:/dev/tty 
  unknown              /dev/tty        4    1-63 console 


------------------------------------------------------------------------------
Summary
------------------------------------------------------------------------------
The /proc file system serves information about the running system. It not only
allows access to process data but also allows you to request the kernel status
by reading files in the hierarchy.

The directory  structure  of /proc reflects the types of information and makes
it easy, if not obvious, where to look for specific data.
------------------------------------------------------------------------------

------------------------------------------------------------------------------
CHAPTER 2: MODIFYING SYSTEM PARAMETERS
------------------------------------------------------------------------------

------------------------------------------------------------------------------
In This Chapter
------------------------------------------------------------------------------
* Modifying kernel parameters by writing into files found in /proc/sys
* Exploring the files which modify certain parameters
* Review of the /proc/sys file tree
------------------------------------------------------------------------------


A very  interesting part of /proc is the directory /proc/sys. This is not only
a source  of  information,  it also allows you to change parameters within the
kernel. Be  very  careful  when attempting this. You can optimize your system,
but you  can  also  cause  it  to  crash.  Never  alter kernel parameters on a
production system.  Set  up  a  development machine and test to make sure that
everything works  the  way  you want it to. You may have no alternative but to
reboot the machine once an error has been made.

To change  a  value,  simply  echo  the new value into the file. An example is
given below  in the section on the file system data. You need to be root to do
this. You  can  create  your  own  boot script to perform this every time your
system boots.

The files  in /proc/sys can be used to fine tune and monitor miscellaneous and
general things  in  the operation of the Linux kernel. Since some of the files
can inadvertently  disrupt  your  system,  it  is  advisable  to  read  both
documentation and  source  before actually making adjustments. In any case, be
very careful  when  writing  to  any  of these files. The entries in /proc may
change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
review the kernel documentation in the directory /usr/src/linux/Documentation.
This chapter  is  heavily  based  on the documentation included in the pre 2.2
kernels, and became part of it in version 2.2.1 of the Linux kernel.

2.1 /proc/sys/fs - File system data
-----------------------------------