2.11 /proc/sys/fs/mqueue - POSIX message queues filesystem
2.12 /proc/<pid>/oom_adj - Adjust the oom-killer score
2.13 /proc/<pid>/oom_score - Display current oom-killer score
+ 2.14 /proc/<pid>/io - Display the IO accounting fields
------------------------------------------------------------------------------
Preface
Table 1-1: Process specific entries in /proc
..............................................................................
- File Content
- cmdline Command line arguments
- cpu Current and last cpu in which it was executed (2.4)(smp)
- cwd Link to the current working directory
- environ Values of environment variables
- exe Link to the executable of this process
- fd Directory, which contains all file descriptors
- maps Memory maps to executables and library files (2.4)
- mem Memory held by this process
- root Link to the root directory of this process
- stat Process status
- statm Process memory status information
- status Process status in human readable form
- wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
- smaps Extension based on maps, presenting the rss size for each mapped file
+ File Content
+ clear_refs Clears page referenced bits shown in smaps output
+ cmdline Command line arguments
+ cpu Current and last cpu in which it was executed (2.4)(smp)
+ cwd Link to the current working directory
+ environ Values of environment variables
+ exe Link to the executable of this process
+ fd Directory, which contains all file descriptors
+ maps Memory maps to executables and library files (2.4)
+ mem Memory held by this process
+ root Link to the root directory of this process
+ stat Process status
+ statm Process memory status information
+ status Process status in human readable form
+ wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
+ smaps Extension based on maps, the rss size for each mapped file
..............................................................................
For example, to get the status information of a process, all you have to do is
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.
+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.
Table 1-2: Contents of the statm files (as of 2.6.8-rc3)
dt number of dirty pages (always 0 on 2.6)
..............................................................................
+
+Table 1-3: Contents of the stat files (as of 2.6.22-rc3)
+..............................................................................
+ Field Content
+ pid process id
+ tcomm 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)
+ ppid process id of the parent process
+ pgrp pgrp of the process
+ sid session id
+ tty_nr tty the process uses
+ tty_pgrp pgrp of the tty
+ flags task flags
+ min_flt number of minor faults
+ cmin_flt number of minor faults with child's
+ maj_flt number of major faults
+ cmaj_flt number of major faults with child's
+ utime user mode jiffies
+ stime kernel mode jiffies
+ cutime user mode jiffies with child's
+ cstime kernel mode jiffies with child's
+ priority priority level
+ nice nice level
+ num_threads number of threads
+ start_time time the process started after system boot
+ vsize virtual memory size
+ rss resident set memory size
+ rsslim current limit in bytes on the rss
+ start_code address above which program text can run
+ end_code address below which program text can run
+ 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)
+ wchan address where process went to sleep
+ 0 (place holder)
+ 0 (place holder)
+ exit_signal signal to send to parent thread on exit
+ task_cpu which CPU the task is scheduled on
+ rt_priority realtime priority
+ policy scheduling policy (man sched_setscheduler)
+ blkio_ticks time spent waiting for block IO
+..............................................................................
+
+
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 1-3. Not all of these will be present in your
+/proc and are listed in Table 1-4. 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 1-3: Kernel info in /proc
+Table 1-4: Kernel info in /proc
..............................................................................
File Content
apm Advanced power management info
mounts Mounted filesystems
net Networking info (see text)
partitions Table of partitions known to the system
- pci Depreciated info of PCI bus (new way -> /proc/bus/pci/,
+ 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)
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.
+directories contains the files shown in table 1-5.
-Table 1-4: IDE controller info in /proc/ide/ide?
+Table 1-5: 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 1-5 are contained in these
+controllers directory. The files listed in table 1-6 are contained in these
directories.
-Table 1-5: IDE device information
+Table 1-6: IDE device information
..............................................................................
File Content
cache The cache
Because the NMI watchdog shares registers with oprofile, by disabling the NMI
watchdog, oprofile may have more registers to utilize.
+maps_protect
+------------
+
+Enables/Disables the protection of the per-process proc entries "maps" and
+"smaps". When enabled, the contents of these files are visible only to
+readers that are allowed to ptrace() the given process.
+
2.4 /proc/sys/vm - The virtual memory subsystem
-----------------------------------------------
you probably should increase the lower_zone_protection setting.
The units of this tunable are fairly vague. It is approximately equal
-to "megabytes". So setting lower_zone_protection=100 will protect around 100
+to "megabytes," so setting lower_zone_protection=100 will protect around 100
megabytes of the lowmem zone from user allocations. It will also make
-those 100 megabytes unavaliable for use by applications and by
+those 100 megabytes unavailable for use by applications and by
pagecache, so there is a cost.
The effects of this tunable may be observed by monitoring
hugetlb_shm_group contains group id that is allowed to create SysV shared
memory segment using hugetlb page.
+hugepages_treat_as_movable
+--------------------------
+
+This parameter is only useful when kernelcore= is specified at boot time to
+create ZONE_MOVABLE for pages that may be reclaimed or migrated. Huge pages
+are not movable so are not normally allocated from ZONE_MOVABLE. A non-zero
+value written to hugepages_treat_as_movable allows huge pages to be allocated
+from ZONE_MOVABLE.
+
+Once enabled, the ZONE_MOVABLE is treated as an area of memory the huge
+pages pool can easily grow or shrink within. Assuming that applications are
+not running that mlock() a lot of memory, it is likely the huge pages pool
+can grow to the size of ZONE_MOVABLE by repeatedly entering the desired value
+into nr_hugepages and triggering page reclaim.
+
laptop_mode
-----------
be dropped. The default settings limit warning messages to one every five
seconds.
+warnings
+--------
+
+This controls console messages from the networking stack that can occur because
+of problems on the network like duplicate address or bad checksums. Normally,
+this should be enabled, but if the problem persists the messages can be
+disabled.
+
+
netdev_max_backlog
------------------
tcp_ecn
-------
-This file controls the use of the ECN bit in the IPv4 headers, this is a new
+This file controls the use of the ECN bit in the IPv4 headers. This is a new
feature about Explicit Congestion Notification, but some routers and firewalls
-block trafic that has this bit set, so it could be necessary to echo 0 to
-/proc/sys/net/ipv4/tcp_ecn, if you want to talk to this sites. For more info
+block traffic that has this bit set, so it could be necessary to echo 0 to
+/proc/sys/net/ipv4/tcp_ecn if you want to talk to these sites. For more info
you could read RFC2481.
tcp_retrans_collapse
command to write value into these files, thereby changing the default settings
of the kernel.
------------------------------------------------------------------------------
+
+2.14 /proc/<pid>/io - Display the IO accounting fields
+-------------------------------------------------------
+
+This file contains IO statistics for each running process
+
+Example
+-------
+
+test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
+[1] 3828
+
+test:/tmp # cat /proc/3828/io
+rchar: 323934931
+wchar: 323929600
+syscr: 632687
+syscw: 632675
+read_bytes: 0
+write_bytes: 323932160
+cancelled_write_bytes: 0
+
+
+Description
+-----------
+
+rchar
+-----
+
+I/O counter: chars read
+The number of bytes which this task has caused to be read from storage. This
+is simply the sum of bytes which this process passed to read() and pread().
+It includes things like tty IO and it is unaffected by whether or not actual
+physical disk IO was required (the read might have been satisfied from
+pagecache)
+
+
+wchar
+-----
+
+I/O counter: chars written
+The number of bytes which this task has caused, or shall cause to be written
+to disk. Similar caveats apply here as with rchar.
+
+
+syscr
+-----
+
+I/O counter: read syscalls
+Attempt to count the number of read I/O operations, i.e. syscalls like read()
+and pread().
+
+
+syscw
+-----
+
+I/O counter: write syscalls
+Attempt to count the number of write I/O operations, i.e. syscalls like
+write() and pwrite().
+
+
+read_bytes
+----------
+
+I/O counter: bytes read
+Attempt to count the number of bytes which this process really did cause to
+be fetched from the storage layer. Done at the submit_bio() level, so it is
+accurate for block-backed filesystems. <please add status regarding NFS and
+CIFS at a later time>
+
+
+write_bytes
+-----------
+
+I/O counter: bytes written
+Attempt to count the number of bytes which this process caused to be sent to
+the storage layer. This is done at page-dirtying time.
+
+
+cancelled_write_bytes
+---------------------
+
+The big inaccuracy here is truncate. If a process writes 1MB to a file and
+then deletes the file, it will in fact perform no writeout. But it will have
+been accounted as having caused 1MB of write.
+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
+from the truncating task's write_bytes, but there is information loss in doing
+that.
+
+
+Note
+----
+
+At its current implementation state, this is a bit racy on 32-bit machines: if
+process A reads process B's /proc/pid/io while process B is updating one of
+those 64-bit counters, process A could see an intermediate result.
+
+
+More information about this can be found within the taskstats documentation in
+Documentation/accounting.
+
+------------------------------------------------------------------------------
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff