Bodo Bauer <bb@ricochet.net>
2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
-move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
+move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
------------------------------------------------------------------------------
Version 1.3 Kernel version 2.2.12
Kernel version 2.4.0-test11-pre4
------------------------------------------------------------------------------
+fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
Table of Contents
-----------------
3.3 /proc/<pid>/io - Display the IO accounting fields
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
3.5 /proc/<pid>/mountinfo - Information about mounts
+ 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
------------------------------------------------------------------------------
subdirectory has the entries listed in Table 1-1.
-Table 1-1: Process specific entries in /proc
+Table 1-1: Process specific entries in /proc
..............................................................................
File Content
clear_refs Clears page referenced bits shown in smaps output
status Process status in human readable form
wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
stack Report full stack trace, enable via CONFIG_STACKTRACE
- smaps Extension based on maps, the rss size for each mapped file
+ smaps a extension based on maps, showing the memory consumption of
+ each mapping
..............................................................................
For example, to get the status information of a process, all you have to do is
read the file /proc/PID/status:
- >cat /proc/self/status
- Name: cat
- State: R (running)
- Pid: 5452
- PPid: 743
+ >cat /proc/self/status
+ Name: cat
+ State: R (running)
+ Tgid: 5452
+ Pid: 5452
+ PPid: 743
TracerPid: 0 (2.4)
- Uid: 501 501 501 501
- Gid: 100 100 100 100
- Groups: 100 14 16
- VmSize: 1112 kB
- VmLck: 0 kB
- VmRSS: 348 kB
- VmData: 24 kB
- VmStk: 12 kB
- VmExe: 8 kB
- VmLib: 1044 kB
- SigPnd: 0000000000000000
- SigBlk: 0000000000000000
- SigIgn: 0000000000000000
- SigCgt: 0000000000000000
- CapInh: 00000000fffffeff
- CapPrm: 0000000000000000
- CapEff: 0000000000000000
-
+ Uid: 501 501 501 501
+ Gid: 100 100 100 100
+ FDSize: 256
+ Groups: 100 14 16
+ VmPeak: 5004 kB
+ VmSize: 5004 kB
+ VmLck: 0 kB
+ VmHWM: 476 kB
+ VmRSS: 476 kB
+ VmData: 156 kB
+ VmStk: 88 kB
+ VmExe: 68 kB
+ VmLib: 1412 kB
+ VmPTE: 20 kb
+ VmSwap: 0 kB
+ Threads: 1
+ SigQ: 0/28578
+ SigPnd: 0000000000000000
+ ShdPnd: 0000000000000000
+ SigBlk: 0000000000000000
+ SigIgn: 0000000000000000
+ SigCgt: 0000000000000000
+ CapInh: 00000000fffffeff
+ CapPrm: 0000000000000000
+ CapEff: 0000000000000000
+ CapBnd: ffffffffffffffff
+ voluntary_ctxt_switches: 0
+ nonvoluntary_ctxt_switches: 1
This shows you nearly the same information you would get if you viewed it with
the ps command. In fact, ps uses the proc file system to obtain its
-information. The statm file contains more detailed information about the
-process memory usage. Its seven fields are explained in Table 1-2. The stat
-file contains details information about the process itself. Its fields are
-explained in Table 1-3.
+information. But you get a more detailed view of the process by reading the
+file /proc/PID/status. It fields are described in table 1-2.
+
+The statm file contains more detailed information about the process
+memory usage. Its seven fields are explained in Table 1-3. The stat file
+contains details information about the process itself. Its fields are
+explained in Table 1-4.
+
+(for SMP CONFIG users)
+For making accounting scalable, RSS related information are handled in
+asynchronous manner and the vaule may not be very precise. To see a precise
+snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
+It's slow but very precise.
+Table 1-2: Contents of the status files (as of 2.6.30-rc7)
+..............................................................................
+ Field Content
+ Name filename of the executable
+ State state (R is running, S is sleeping, D is sleeping
+ in an uninterruptible wait, Z is zombie,
+ T is traced or stopped)
+ Tgid thread group ID
+ Pid process id
+ PPid process id of the parent process
+ TracerPid PID of process tracing this process (0 if not)
+ Uid Real, effective, saved set, and file system UIDs
+ Gid Real, effective, saved set, and file system GIDs
+ FDSize number of file descriptor slots currently allocated
+ Groups supplementary group list
+ VmPeak peak virtual memory size
+ VmSize total program size
+ VmLck locked memory size
+ VmHWM peak resident set size ("high water mark")
+ VmRSS size of memory portions
+ VmData size of data, stack, and text segments
+ VmStk size of data, stack, and text segments
+ VmExe size of text segment
+ VmLib size of shared library code
+ VmPTE size of page table entries
+ VmSwap size of swap usage (the number of referred swapents)
+ Threads number of threads
+ SigQ number of signals queued/max. number for queue
+ SigPnd bitmap of pending signals for the thread
+ ShdPnd bitmap of shared pending signals for the process
+ SigBlk bitmap of blocked signals
+ SigIgn bitmap of ignored signals
+ SigCgt bitmap of catched signals
+ CapInh bitmap of inheritable capabilities
+ CapPrm bitmap of permitted capabilities
+ CapEff bitmap of effective capabilities
+ CapBnd bitmap of capabilities bounding set
+ Cpus_allowed mask of CPUs on which this process may run
+ Cpus_allowed_list Same as previous, but in "list format"
+ Mems_allowed mask of memory nodes allowed to this process
+ Mems_allowed_list Same as previous, but in "list format"
+ voluntary_ctxt_switches number of voluntary context switches
+ nonvoluntary_ctxt_switches number of non voluntary context switches
+..............................................................................
-Table 1-2: Contents of the statm files (as of 2.6.8-rc3)
+Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
..............................................................................
Field Content
size total program size (pages) (same as VmSize in status)
..............................................................................
-Table 1-3: Contents of the stat files (as of 2.6.22-rc3)
+Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
..............................................................................
Field Content
pid process id
start_stack address of the start of the stack
esp current value of ESP
eip current value of EIP
- pending bitmap of pending signals (obsolete)
- blocked bitmap of blocked signals (obsolete)
- sigign bitmap of ignored signals (obsolete)
- sigcatch bitmap of catched signals (obsolete)
+ pending bitmap of pending signals
+ blocked bitmap of blocked signals
+ sigign bitmap of ignored signals
+ sigcatch bitmap of catched signals
wchan address where process went to sleep
0 (place holder)
0 (place holder)
rt_priority realtime priority
policy scheduling policy (man sched_setscheduler)
blkio_ticks time spent waiting for block IO
+ gtime guest time of the task in jiffies
+ cgtime guest time of the task children in jiffies
..............................................................................
+The /proc/PID/maps file containing the currently mapped memory regions and
+their access permissions.
+
+The format is:
+
+address perms offset dev inode pathname
+
+08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
+08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
+0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
+a7cb1000-a7cb2000 ---p 00000000 00:00 0
+a7cb2000-a7eb2000 rw-p 00000000 00:00 0
+a7eb2000-a7eb3000 ---p 00000000 00:00 0
+a7eb3000-a7ed5000 rw-p 00000000 00:00 0
+a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
+a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
+a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
+a800b000-a800e000 rw-p 00000000 00:00 0
+a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
+a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
+a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
+a8024000-a8027000 rw-p 00000000 00:00 0
+a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
+a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
+a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
+aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
+ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
+
+where "address" is the address space in the process that it occupies, "perms"
+is a set of permissions:
+
+ r = read
+ w = write
+ x = execute
+ s = shared
+ p = private (copy on write)
+
+"offset" is the offset into the mapping, "dev" is the device (major:minor), and
+"inode" is the inode on that device. 0 indicates that no inode is associated
+with the memory region, as the case would be with BSS (uninitialized data).
+The "pathname" shows the name associated file for this mapping. If the mapping
+is not associated with a file:
+
+ [heap] = the heap of the program
+ [stack] = the stack of the main process
+ [vdso] = the "virtual dynamic shared object",
+ the kernel system call handler
+
+ or if empty, the mapping is anonymous.
+
+
+The /proc/PID/smaps is an extension based on maps, showing the memory
+consumption for each of the process's mappings. For each of mappings there
+is a series of lines such as the following:
+
+08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
+Size: 1084 kB
+Rss: 892 kB
+Pss: 374 kB
+Shared_Clean: 892 kB
+Shared_Dirty: 0 kB
+Private_Clean: 0 kB
+Private_Dirty: 0 kB
+Referenced: 892 kB
+Swap: 0 kB
+KernelPageSize: 4 kB
+MMUPageSize: 4 kB
+
+The first of these lines shows the same information as is displayed for the
+mapping in /proc/PID/maps. The remaining lines show the size of the mapping,
+the amount of the mapping that is currently resident in RAM, the "proportional
+set size” (divide each shared page by the number of processes sharing it), the
+number of clean and dirty shared pages in the mapping, and the number of clean
+and dirty private pages in the mapping. The "Referenced" indicates the amount
+of memory currently marked as referenced or accessed.
+
+This file is only present if the CONFIG_MMU kernel configuration option is
+enabled.
+
+The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
+bits on both physical and virtual pages associated with a process.
+To clear the bits for all the pages associated with the process
+ > echo 1 > /proc/PID/clear_refs
+
+To clear the bits for the anonymous pages associated with the process
+ > echo 2 > /proc/PID/clear_refs
+
+To clear the bits for the file mapped pages associated with the process
+ > echo 3 > /proc/PID/clear_refs
+Any other value written to /proc/PID/clear_refs will have no effect.
+
1.2 Kernel data
---------------
Similar to the process entries, the kernel data files give information about
the running kernel. The files used to obtain this information are contained in
-/proc and are listed in Table 1-4. Not all of these will be present in your
+/proc and are listed in Table 1-5. Not all of these will be present in your
system. It depends on the kernel configuration and the loaded modules, which
files are there, and which are missing.
-Table 1-4: Kernel info in /proc
+Table 1-5: Kernel info in /proc
..............................................................................
File Content
apm Advanced power management info
modules List of loaded modules
mounts Mounted filesystems
net Networking info (see text)
+ pagetypeinfo Additional page allocator information (see text) (2.5)
partitions Table of partitions known to the system
pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
decoupled by lspci (2.4)
rtc Real time clock
scsi SCSI info (see text)
slabinfo Slab pool info
+ softirqs softirq usage
stat Overall statistics
swaps Swap space utilization
sys See chapter 2
IRQs which have not yet been allocated/activated, and hence which lack a
/proc/irq/[0-9]* directory.
+The node file on an SMP system shows the node to which the device using the IRQ
+reports itself as being attached. This hardware locality information does not
+include information about any possible driver locality preference.
+
prof_cpu_mask specifies which CPUs are to be profiled by the system wide
profiler. Default value is ffffffff (all cpus).
Node 0, zone Normal 1 0 0 1 101 8 ...
Node 0, zone HighMem 2 0 0 1 1 0 ...
-Memory fragmentation is a problem under some workloads, and buddyinfo is a
+External fragmentation is a problem under some workloads, and buddyinfo is a
useful tool for helping diagnose these problems. Buddyinfo will give you a
clue as to how big an area you can safely allocate, or why a previous
allocation failed.
ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
available in ZONE_NORMAL, etc...
+More information relevant to external fragmentation can be found in
+pagetypeinfo.
+
+> cat /proc/pagetypeinfo
+Page block order: 9
+Pages per block: 512
+
+Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
+Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
+Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
+Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
+Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
+Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
+Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
+Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
+Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
+Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
+Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
+
+Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
+Node 0, zone DMA 2 0 5 1 0
+Node 0, zone DMA32 41 6 967 2 0
+
+Fragmentation avoidance in the kernel works by grouping pages of different
+migrate types into the same contiguous regions of memory called page blocks.
+A page block is typically the size of the default hugepage size e.g. 2MB on
+X86-64. By keeping pages grouped based on their ability to move, the kernel
+can reclaim pages within a page block to satisfy a high-order allocation.
+
+The pagetypinfo begins with information on the size of a page block. It
+then gives the same type of information as buddyinfo except broken down
+by migrate-type and finishes with details on how many page blocks of each
+type exist.
+
+If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
+from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can
+make an estimate of the likely number of huge pages that can be allocated
+at a given point in time. All the "Movable" blocks should be allocatable
+unless memory has been mlock()'d. Some of the Reclaimable blocks should
+also be allocatable although a lot of filesystem metadata may have to be
+reclaimed to achieve this.
+
..............................................................................
meminfo:
0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
pages=10 vmalloc N0=10
+..............................................................................
+
+softirqs:
+
+Provides counts of softirq handlers serviced since boot time, for each cpu.
+
+> cat /proc/softirqs
+ CPU0 CPU1 CPU2 CPU3
+ HI: 0 0 0 0
+ TIMER: 27166 27120 27097 27034
+ NET_TX: 0 0 0 17
+ NET_RX: 42 0 0 39
+ BLOCK: 0 0 107 1121
+ TASKLET: 0 0 0 290
+ SCHED: 27035 26983 26971 26746
+ HRTIMER: 0 0 0 0
+ RCU: 1678 1769 2178 2250
+
+
1.3 IDE devices in /proc/ide
----------------------------
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 1-5.
+directories contains the files shown in table 1-6.
-Table 1-5: IDE controller info in /proc/ide/ide?
+Table 1-6: IDE controller info in /proc/ide/ide?
..............................................................................
File Content
channel IDE channel (0 or 1)
..............................................................................
Each device connected to a controller has a separate subdirectory in the
-controllers directory. The files listed in table 1-6 are contained in these
+controllers directory. The files listed in table 1-7 are contained in these
directories.
-Table 1-6: IDE device information
+Table 1-7: IDE device information
..............................................................................
File Content
cache The cache
1.4 Networking info in /proc/net
--------------------------------
-The subdirectory /proc/net follows the usual pattern. Table 1-6 shows the
+The subdirectory /proc/net follows the usual pattern. Table 1-8 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.
+support this. Table 1-9 lists the files and their meaning.
-Table 1-6: IPv6 info in /proc/net
+Table 1-8: IPv6 info in /proc/net
..............................................................................
File Content
udp6 UDP sockets (IPv6)
..............................................................................
-Table 1-7: Network info in /proc/net
+Table 1-9: Network info in /proc/net
..............................................................................
File Content
arp Kernel ARP table
...] 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
+In addition, each Channel Bond interface has its 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
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.
+These directories contain the four files shown in Table 1-10.
-Table 1-8: Files in /proc/parport
+Table 1-10: Files in /proc/parport
..............................................................................
File Content
autoprobe Any IEEE-1284 device ID information that has been acquired.
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.
+this directory, as shown in Table 1-11.
-Table 1-9: Files in /proc/tty
+Table 1-11: Files in /proc/tty
..............................................................................
File Content
drivers list of drivers and their usage
since the system first booted. For a quick look, simply cat the file:
> cat /proc/stat
- cpu 2255 34 2290 22625563 6290 127 456 0
- cpu0 1132 34 1441 11311718 3675 127 438 0
- cpu1 1123 0 849 11313845 2614 0 18 0
+ cpu 2255 34 2290 22625563 6290 127 456 0 0
+ cpu0 1132 34 1441 11311718 3675 127 438 0 0
+ cpu1 1123 0 849 11313845 2614 0 18 0 0
intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
ctxt 1990473
btime 1062191376
processes 2915
procs_running 1
procs_blocked 0
+ softirq 183433 0 21755 12 39 1137 231 21459 2263
The very first "cpu" line aggregates the numbers in all of the other "cpuN"
lines. These numbers identify the amount of time the CPU has spent performing
- irq: servicing interrupts
- softirq: servicing softirqs
- steal: involuntary wait
+- guest: running a normal guest
+- guest_nice: running a niced guest
The "intr" line gives counts of interrupts serviced since boot time, for each
of the possible system interrupts. The first column is the total of all
includes (but is not limited to) those created by calls to the fork() and
clone() system calls.
-The "procs_running" line gives the number of processes currently running on
-CPUs.
+The "procs_running" line gives the total number of threads that are
+running or ready to run (i.e., the total number of runnable threads).
The "procs_blocked" line gives the number of processes currently blocked,
waiting for I/O to complete.
+The "softirq" line gives counts of softirqs serviced since boot time, for each
+of the possible system softirqs. The first column is the total of all
+softirqs serviced; each subsequent column is the total for that particular
+softirq.
+
1.9 Ext4 file system parameters
------------------------------
/proc/fs/ext4. Each mounted filesystem will have a directory in
/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
/proc/fs/ext4/dm-0). The files in each per-device directory are shown
-in Table 1-10, below.
+in Table 1-12, below.
-Table 1-10: Files in /proc/fs/ext4/<devname>
+Table 1-12: Files in /proc/fs/ext4/<devname>
..............................................................................
File Content
mb_groups details of multiblock allocator buddy cache of free blocks
- mb_history multiblock allocation history
..............................................................................
3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
------------------------------------------------------
-This file can be used to adjust the score used to select which processes should
-be killed in an out-of-memory situation. The oom_adj value is a characteristic
-of the task's mm, so all threads that share an mm with pid will have the same
-oom_adj value. A high value will increase the likelihood of this process being
-killed by the oom-killer. Valid values are in the range -16 to +15 as
-explained below and a special value of -17, which disables oom-killing
-altogether for threads sharing pid's mm.
+This file can be used to adjust the score used to select which processes
+should be killed in an out-of-memory situation. Giving it a high score will
+increase the likelihood of this process being killed by the oom-killer. Valid
+values are in the range -16 to +15, plus the special value -17, which disables
+oom-killing altogether for this process.
The process to be killed in an out-of-memory situation is selected among all others
based on its badness score. This value equals the original memory size of the process
are the prime candidates to be killed. Having only one 'hungry' child will make
parent less preferable than the child.
-/proc/<pid>/oom_adj cannot be changed for kthreads since they are immune from
-oom-killing already.
-
/proc/<pid>/oom_score shows process' current badness score.
The following heuristics are then applied:
* if the task was reniced, its score doubles
* superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE
or CAP_SYS_RAWIO) have their score divided by 4
- * if oom condition happened in one cpuset and checked task does not belong
+ * if oom condition happened in one cpuset and checked process does not belong
to it, its score is divided by 8
* the resulting score is multiplied by two to the power of oom_adj, i.e.
points <<= oom_adj when it is positive and
In other words: The number of bytes which this process caused to not happen,
by truncating pagecache. A task can cause "negative" IO too. If this task
truncates some dirty pagecache, some IO which another task has been accounted
-for (in it's write_bytes) will not be happening. We _could_ just subtract that
+for (in its write_bytes) will not be happening. We _could_ just subtract that
from the truncating task's write_bytes, but there is information loss in doing
that.
Documentation/filesystems/sharedsubtree.txt
+
+3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
+--------------------------------------------------------
+These files provide a method to access a tasks comm value. It also allows for
+a task to set its own or one of its thread siblings comm value. The comm value
+is limited in size compared to the cmdline value, so writing anything longer
+then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
+comm value.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff