2.9 Appletalk
2.10 IPX
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
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Preface
..............................................................................
File Content
cmdline Command line arguments
- cpu Current and last cpu in wich it was executed (2.4)(smp)
+ 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
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
..............................................................................
For example, to get the status information of a process, all you have to do is
> cat /proc/irq/0/smp_affinity
ffffffff
-It's a bitmask, in wich you can specify wich CPUs can handle the IRQ, you can
+It's a bitmask, in which you can specify which CPUs can handle the IRQ, you can
set it by doing:
> echo 1 > /proc/irq/prof_cpu_mask
This means that only the first CPU will handle the IRQ, but you can also echo 5
-wich means that only the first and fourth CPU can handle the IRQ.
+which means that only the first and fourth CPU can handle the IRQ.
The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
between all the CPUs which are allowed to handle it. As usual the kernel has
this memory, making it slower to access than lowmem.
LowTotal:
LowFree: Lowmem is memory which can be used for everything that
- highmem can be used for, but it is also availble for the
+ highmem can be used for, but it is also available for the
kernel's use for its own data structures. Among many
other things, it is where everything from the Slab is
allocated. Bad things happen when you're out of lowmem.
Dirty: Memory which is waiting to get written back to the disk
Writeback: Memory which is actively being written back to the disk
Mapped: files which have been mmaped, such as libraries
- Slab: in-kernel data structures cache
+ Slab: in-kernel data structures cache
CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
this is the total amount of memory currently available to
be allocated on the system. This limit is only adhered to
Represents the number of free inodes. Ie. The number of inuse inodes is
(nr_inodes - nr_free_inodes).
-super-nr and super-max
-----------------------
-
-Again, super block structures are allocated by the kernel, but not freed. The
-file super-max contains the maximum number of super block handlers, where
-super-nr shows the number of currently allocated ones.
-
-Every mounted file system needs a super block, so if you plan to mount lots of
-file systems, you may want to increase these numbers.
-
aio-nr and aio-max-nr
---------------------
NMI switch that most IA32 servers have fires unknown NMI up, for example.
If a system hangs up, try pressing the NMI switch.
-[NOTE]
- This function and oprofile share a NMI callback. Therefore this function
- cannot be enabled when oprofile is activated.
- And NMI watchdog will be disabled when the value in this file is set to
- non-zero.
+nmi_watchdog
+------------
+
+Enables/Disables the NMI watchdog on x86 systems. When the value is non-zero
+the NMI watchdog is enabled and will continuously test all online cpus to
+determine whether or not they are still functioning properly.
+
+Because the NMI watchdog shares registers with oprofile, by disabling the NMI
+watchdog, oprofile may have more registers to utilize.
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
overcommit_memory
-----------------
-This file contains one value. The following algorithm is used to decide if
-there's enough memory: if the value of overcommit_memory is positive, then
-there's always enough memory. This is a useful feature, since programs often
-malloc() huge amounts of memory 'just in case', while they only use a small
-part of it. Leaving this value at 0 will lead to the failure of such a huge
-malloc(), when in fact the system has enough memory for the program to run.
+Controls overcommit of system memory, possibly allowing processes
+to allocate (but not use) more memory than is actually available.
+
+
+0 - Heuristic overcommit handling. Obvious overcommits of
+ address space are refused. Used for a typical system. It
+ ensures a seriously wild allocation fails while allowing
+ overcommit to reduce swap usage. root is allowed to
+ allocate slightly more memory in this mode. This is the
+ default.
+
+1 - Always overcommit. Appropriate for some scientific
+ applications.
+
+2 - Don't overcommit. The total address space commit
+ for the system is not permitted to exceed swap plus a
+ configurable percentage (default is 50) of physical RAM.
+ Depending on the percentage you use, in most situations
+ this means a process will not be killed while attempting
+ to use already-allocated memory but will receive errors
+ on memory allocation as appropriate.
+
+overcommit_ratio
+----------------
+
+Percentage of physical memory size to include in overcommit calculations
+(see above.)
+
+Memory allocation limit = swapspace + physmem * (overcommit_ratio / 100)
-On the other hand, enabling this feature can cause you to run out of memory
-and thrash the system to death, so large and/or important servers will want to
-set this value to 0.
+ swapspace = total size of all swap areas
+ physmem = size of physical memory in system
nr_hugepages and hugetlb_shm_group
----------------------------------
unnecessary page faults in thrashing situation. The unit of the value is
second. The value would be useful to tune thrashing behavior.
+drop_caches
+-----------
+
+Writing to this will cause the kernel to drop clean caches, dentries and
+inodes from memory, causing that memory to become free.
+
+To free pagecache:
+ echo 1 > /proc/sys/vm/drop_caches
+To free dentries and inodes:
+ echo 2 > /proc/sys/vm/drop_caches
+To free pagecache, dentries and inodes:
+ echo 3 > /proc/sys/vm/drop_caches
+
+As this is a non-destructive operation and dirty objects are not freeable, the
+user should run `sync' first.
+
+
2.5 /proc/sys/dev - Device specific parameters
----------------------------------------------
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
default is to use the BSD compatible interpretation of the urgent pointer
pointing to the first byte after the urgent data. The RFC793 interpretation is
to have it point to the last byte of urgent data. Enabling this option may
-lead to interoperatibility problems. Disabled by default.
+lead to interoperability problems. Disabled by default.
tcp_syncookies
--------------
These parameters are used to limit how many ICMP destination unreachable to
send from the host in question. ICMP destination unreachable messages are
-sent when we can not reach the next hop, while trying to transmit a packet.
+sent when we cannot reach the next hop while trying to transmit a packet.
It will also print some error messages to kernel logs if someone is ignoring
our ICMP redirects. The higher the error_cost factor is, the fewer
destination unreachable and error messages will be let through. Error_burst
In the interface directories you'll find the following entries:
-base_reachable_time
--------------------
+base_reachable_time, base_reachable_time_ms
+-------------------------------------------
A base value used for computing the random reachable time value as specified
in RFC2461.
-retrans_time
-------------
+Expression of base_reachable_time, which is deprecated, is in seconds.
+Expression of base_reachable_time_ms is in milliseconds.
-The time, expressed in jiffies (1/100 sec), between retransmitted Neighbor
-Solicitation messages. Used for address resolution and to determine if a
-neighbor is unreachable.
+retrans_time, retrans_time_ms
+-----------------------------
+
+The time between retransmitted Neighbor Solicitation messages.
+Used for address resolution and to determine if a neighbor is
+unreachable.
+
+Expression of retrans_time, which is deprecated, is in 1/100 seconds (for
+IPv4) or in jiffies (for IPv6).
+Expression of retrans_time_ms is in milliseconds.
unres_qlen
----------
Maximum queue length of the delayed proxy arp timer. (see proxy_delay).
-app_solcit
+app_solicit
----------
Determines the number of requests to send to the user level ARP daemon. Use 0
maximum message size value (it is every message queue's attribute set during
its creation).
+2.12 /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. 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.
+
+2.13 /proc/<pid>/oom_score - Display current oom-killer score
+-------------------------------------------------------------
+
+------------------------------------------------------------------------------
+This file can be used to check the current score used by the oom-killer is for
+any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
+process should be killed in an out-of-memory situation.
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Summary
git://git.onelab.eu / linux-2.6.git / blobdiff