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Full Discussion: Swap memory
Operating Systems Linux Red Hat Swap memory Post 302856971 by jim mcnamara on Wednesday 25th of September 2013 07:20:36 AM
Old 09-25-2013
You can force a process to start out mostly in swap, but if the process runs at all it will wind up in RAM. Running something totally from swap is a bad idea, and if allowed, it results in a real performance drag called thrashing. The swapped process runs 100's of time slower and can seriously degrade the whole system. For every other process on the system.

If you got this idea from seeing how much memory a service is using, you may have misunderstood. A lot of the working set of a process is in shared memory. All processes use this shared memory at the same time. If each of the required system processes (services among them) had nothing but private memory, it likely would have eaten most of system memory before you even logged onto a newly booted box.

You may want to rethink this swap idea.
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memx(8) 						      System Manager's Manual							   memx(8)

NAME
memx - memory exerciser SYNOPSIS
/usr/field/memx -s [-h] [-ofile] [-ti] [-mj] [-pk] OPTIONS
The memx options are as follows: Print the help message for the memx command. Disables automatic shared memory testing. Save diagnostic output in file. Run time in minutes (i). The default is to run until the process receives a CTRL-C or a kill -15 pid command. The memory size in bytes (j) to be tested by each spawned process. Must be greater than 4095. The default is (total-memory)/20. The number of pro- cesses to spawn (k). The default is 20. The maximum is also 20. DESCRIPTION
The memx memory exerciser spawns processes to exercise memory by writing and reading three patterns: 1's and 0's, 0's and 1's, and a random pattern. You specify the number of processes to spawn and the size of memory to be tested by each process. If the shmx Shared Memory exerciser is present, it will be the first process spawned; the remaining processes are standard memory exercisers. The memx exerciser will run until the process receives a CTRL-C or a kill -15 pid command. A logfile for you to examine and then remove is created in the current working directory. If there are errors in the logfile, check the syslog file where the driver and kernel error messages are saved. RESTRICTIONS
The memx exerciser is restricted by the size of the available swap space. The size of the swap space and the size of internal memory available determines how many processes can run on the system. For example, If there is 16 Mbytes of swap space and 16 Mbytes of memory, all of the swap space would be used if all 20 spawned memory exercisers are running. In that event, no new processes would be able to run. On systems with large amounts of memory and small swap space, you must restrict the number of memory exercisers and/or the size of memory being tested. If there is a need to run a system exerciser over an NFS link or on a diskless system there are some restrictions. For exercisers that need to write into a file system, such as fsx(8), the target file system must be writable by root. Also, the directory in which any of the exercisers are executed must be writable by root because temporary files are written into the current directory. These latter restrictions are sometimes difficult to overcome because often NFS file systems are mounted in a way that prevents root from writing into them. Some of the restrictions may be overcome by copying the exerciser to another directory and then executing it. You should specify the -s option to disable automatic shared memory testing, which is not supported. EXAMPLES
The following example tests all of memory by running 20 spawned processes until a CTRL-C or kill -15 pid command is received: % /usr/field/memx The following example runs 10 spawned processes, memory size 500,000 bytes, for 180 minutes in the background. % /usr/field/memx -t180 -m500000 -p10 & SEE ALSO
Commands: cmx(8), diskx(8), fsx(8), shmx(8), tapex(8) memx(8)
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