03-07-2008
Quote:
Originally Posted by
bakunin
This is why i have offered "ps" as a means to find out how much memory is in fact used by processs. Add to this number the shared memory segments and you get a number you can compare to the "fre" column in vmstat. This is the best approximation to whatever you might define as "free".
Using "ps" may be a valid means. IMHO svmon (-G) is somewhat better up to this job (how much memory is free) as it keeps away from me some overly complex procedure of summing up every process's memory size to find out how much memory overall is needed. Furthermore there is no need to consider that memory segments can be used by multiple processes when you use svmon. Subtract the (active) "virtual" memory from the "size" and you get a good impression on how much memory is "free"
Quote:
Originally Posted by
bakunin
In my wording "free" means "unused" and vice versa, not "maybe freeable by arbitrarily complex procedures". The AIX kernel tries to use memory as efficient as possible and might show relatively little memory as free when it could do with significantly less memory too - that doesn't mean that the number is incorrect, but that maybe processes stay in memory which would otherwise have been swapped out or all sorts of buffers being full-length whereas they would be decreased in size in case of memory shortage.
I agree with the kernel thing - but in case there might have been some misunderstanding: I wasn't up to learn what you, bakunin, understand by "free" memory. I was rather keen to find out what the OP wanted to know in the first place.
'Cause I thought this thread was about some AIX specific memory handling which might be confusing for a beginner as there *seems* to be almost no free memory
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IPCS(1) BSD General Commands Manual IPCS(1)
NAME
ipcs -- report System V interprocess communication facilities status
SYNOPSIS
ipcs [-abcMmopQqSsTt]
DESCRIPTION
The ipcs utility provides information on System V interprocess communication (IPC) facilities on the system.
The options are as follows:
-a Show the maximum amount of information possible when displaying active semaphores, message queues, and shared memory segments. (This
is shorthand for specifying the -b, -c, -o, -p, and -t options.)
-b Show the maximum allowed sizes for active semaphores, message queues, and shared memory segments. The ``maximum allowed size'' is
the maximum number of bytes in a message on a message queue, the size of a shared memory segment, or the number of semaphores in a
set of semaphores.
-c Show the creator's name and group for active semaphores, message queues, and shared memory segments.
-M Display system information about shared memory.
-m Display information about active shared memory segments.
-o Show outstanding usage for active message queues, and shared memory segments. The ``outstanding usage'' is the number of messages in
a message queue, or the number of processes attached to a shared memory segment.
-p Show the process ID information for active semaphores, message queues, and shared memory segments. The ``process ID information'' is
the last process to send a message to or receive a message from a message queue, the process that created a semaphore, or the last
process to attach or detach a shared memory segment.
-Q Display system information about messages queues.
-q Display information about active message queues.
-S Display system information about semaphores.
-s Display information about active semaphores.
-T Display system information about shared memory, message queues and semaphores.
-t Show access times for active semaphores, message queues, and shared memory segments. The access times is the time of the last con-
trol operation on an IPC object, the last send or receive of a message, the last attach or detach of a shared memory segment, or the
last operation on a semaphore.
If none of the -M, -m, -Q, -q, -S, or -s options are specified, information about all active IPC facilities is listed.
RESTRICTIONS
System data structures may change while ipcs is running; the output of ipcs is not guaranteed to be consistent.
BUGS
This manual page is woefully incomplete, because it does not at all attempt to explain the information printed by ipcs.
SEE ALSO
ipcrm(1)
AUTHORS
Thorsten Lockert <tholo@sigmasoft.com>
BSD
June 18, 1994 BSD