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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
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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
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
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.
-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.
+
+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 slighly 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)
+
+ 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
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git://git.onelab.eu / linux-2.6.git / blobdiff