In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.

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How to enable deduplication in linux [on hold]

I want to enable deduplication in Linux. I am not sure whether its enable by default or not. If not please tell me the command for enabling deduplication in Linux.
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Questions on /dev/mem, dumping using dd, and .bin and .rom formats

Following @ack 's answer on How to dump BIOS data to a file I would like to know: 1) when one is dumping memory from /dev/mem, is the file data in binary or some other format? I have done a dump ...
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36 views

How to convert from virtual address to physical address and back? [migrated]

I'm given a task to write an application that will talk to a device. However this is not a driver since device is still being developed and the application is intended to exercises its first revision. ...
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0answers
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Flash an OS to an eMMC, from uSD with larger capacity than eMMC

With a Debian distro installed into a 8GB uSD (although uSD memory is almost free), I need to flash this distro into the 4GB eMMC of a BeagleBone Black board, based on AM335x SoC. The S2 switch ...
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3answers
2k views

Discrepancy between reported used memory and sum of application memory usage

I'm running a desktop system that quite regularly suffers from lack of memory, this prompted me to investigate what causes the issue in the first place. Problem is, there's no single process that ...
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1answer
282 views

What is using 4GB of memory? (Not cache, not a process, not slab, not shm)

We have some EC2 servers that experience a memory leak over days or weeks. Eventually there gets to be many GB of memory that is used (according to tools like free and htop) and, if we don't restart ...
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0answers
1k views

About mem and vmem

I am working with a cluster machine running under linux. I have a shell script that uses mpirun to submit my jobs to the cluster machine. In that same script, I can choose the number of nodes that ...
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1answer
31 views

Embedded Linux OOM - help with lost RAM

I have little Linux system with 256MB RAM. I'm little bit confused, where the RAM may be lost? It is running old linux kernel 2.6.38 and I'm not able to ubgrade it (some specific ARM board). SHM and ...
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1answer
2k views

Is it possible to find the physical address range of a DIMM?

I note that SMBios Type 20 would help here, but it's optional as of version 2.5 (2006-09-05) pp. 25, L796, and pp. 131, whereas types 16, 17 and 19 are mandatory, but don't quite help. Physical ...
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5answers
21k views

Swap usage too high?

I have a Debian Sid box, freshly installed about a month ago, with no desktop apps running at the moment. Any command I try to run (via ssh) makes the hard disk work very hard. The system worked ...
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2answers
21k views

How to dump memory image from linux system?

I know to dump memory images in Window. (eg-dumpit) But I don't know how to dump memory images in Linux. I wanna get memory images in Linux and from linux to linux with ssh connection or something. ...
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1answer
585 views

What are the differences in shared memory between early and modern Unix systems?

How could processes share memory in early versions of Unix? How does this compare with modern implementations of shared memory?
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1answer
4k views

What is equivalent to Mac's purge in Linux? [duplicate]

In Mac I use purge to free up some memory. What is equivalent to it in Linux(Ubuntu Server)? apt-get install purge gave me nothing. If you are no familiar with Mac's purge here is it's man page: ...
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i whant to clean the shared and the buff/cache memory [duplicate]

I want to clean the shared and the buff/cache memory, I'm not expert in linux but I want to learn. I have 2 gb of ram when i go through firefox the memory used is 900-1000 mb is this normal?? ...
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2answers
2k views

An oom killer thats baffling me

I am not able to understand why would kernel issue this oom killer when I see enough memory is available: Also why are there so many kernel cache pages allocated? I say enough memory is available ...
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1answer
6k views

httpd memory usage very high

I host a wordpress site on my server which has 2GB mem, I have used some cache plugin, but when I type ps -eo "%C : %p : %z : %a" | sort -k5 -nr in SSH, I see the httpd memory usage is very high. 15....
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4answers
950 views

How to force Linux kernel to “freeze” (or nearly freeze) for a few hundred milliseconds

We are running a real-time process on a non real-time kernel (CentOS 6), and this is probably not going to change. We have a streaming video application that requires about 500 MB/s of PCIe traffic ...
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1answer
986 views

Java/malloc memory corruption error when running SDK Android Manager

I want to install Android SDK, so I manually installed Java JDK 7u51, downloaded SDK ADT bundle for Linux x64, and tried to run it. When I run android, the SDK manager windows hangs halfway through ...
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GNU/Linux OOM (out of memory) freezes - solution ideas

Explanation While working with older machine with swap on and 2 GB ram, I frequently encounter behaviour well described as freeze: here, what is the best way to prevent out of memory oom freezes on ...
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2answers
26 views

How to use top in a shell script to track memory consumption of a process?

I was wondering if there was a way to use top or another program to track the memory consumption of a script I will be running. I was using runtime.totalMemory - runtime.freeMemory But that'...
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0answers
26 views

How to specify memory region for ramdrive

We are setting up a linux based benchmarking cluster. Each node is going to be a headless, diskless machine, booted via tftp, the OS copied to a local ramdrive, and the same ramdrive is used as local ...
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4answers
3k views

How much RAM needed for preventing use swap?

At my system always available some "Free" and "Inactive" memory, but sometimes system move couple megabytes to swap. Per night it maybe around 100MB, but for a few days in swap could be more than ...
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1answer
3k views

Optimised ZFS in low RAM environment feasibility?

I am currently setting up a file server and have come to the point of actually setting up the data drives. The system has 4 drives (one OS disk, 3 data disks). The OS disk is formatted as ext4 and ...
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2answers
4k views

System hanging when it runs out of memory

I've got an eeePC 900a: it has a 8GB flash as disk and only 1GB of RAM. The Linux distribution installed on it is ArchLinux. When the system runs out of memory it becomes extremely unresponsive: it ...
5
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1answer
673 views

When files are being moved are they stored in a memory?

When I move a file using the mv command, is this file first read, fully cached into a memory and then saved as another file? Or is it the same as writing while read line; do echo "$line" >>...
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3answers
77 views

Get chrome's total memory usage

Since google chrome/chromium spawn multiple processes it's harder to see how much total memory these processes use in total. Is there an easy way to see how much total memory a series of connected ...
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4answers
20k views

How to get free memory on AIX?

How can I see the free memory on an AIX? There is no free -m under it. AIX oslevel: 6100-03-03-0943
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0answers
27 views

Entire Harddrive to linux swap

I have an old hard drive that is less than 50Gb and a computer that only has about 4Gb of ram (and ~250Gb main HDD). I was thinking about using the second drive as an entire drive linux-swap partition....
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0answers
108 views

Memory Leak trackdown

I have a server running Red Hat Enterprise Linux Server release 6.7. The server runs a number of java processes including a tomcat server with nginx webserver. The server has 12 GB of ram allocated ...
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4answers
11k views

Bash script that automatically kills processes when CPU/memory usage gets too high

I have created a script that kills processes if CPU and/or memory usage hits 80%. It creates a list of killed processes when this happens. What can I do to improve it? while [ 1 ]; do echo echo ...
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1answer
26 views

Virtualbox memory not reflected in its cgroup

I've trying to limit the amount of memory a user can use using cgroups (using Ubuntu 16.04 with systemd). After setting the MemoryLimit property of user-.slice I can see the change reflected in its ...
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1answer
27 views

Disable OS-level caching

I want to be able to prevent the OS from caching in memory either: A particular file, or Any file a particular process accesses (i.e. by specifying a pid) Either would be helpful since I don't ...
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0answers
39 views

Total memory decreased when increasing swap file?

I am running a low-end server with about 1GB RAM and I was trying to optimize my ram. But after increasing my swap file and emptying the buffers, my total ram, judging from free -m, have lowered from ...
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1answer
30 views

Do .so files get loaded as a whole into memory?

When a program causes a .so file to be loaded into memory, does is get loaded as a whole, or or does it only load the necessary "chunks"?
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0answers
127 views

Process killed by OOM killer when plenty of memory apparently free

I'm working on an embedded ARM-based platform. 32-bit, 512MB of RAM, no swap. Linux 3.10.53 (some variety of Ubuntu, if that's relevant). Some code I'm working on is getting consistently oom-killed, ...
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0answers
60 views

Debian 8 performance problems with good hardware

I bought about 6 months ago a good laptop (Lenovo ThinkPad E550 : Intel Core i5-5200U, 8 GO DDR3, AMD Radeon R7 M260) and installed Debian Jessie with Gnome 3 (no unity) on it. The system worked fine ...
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2answers
44 views

How much memory is a specific user using

Is it possible to find out how much memory I am using on a multiuser linux machine? I want to know whether I am using a lot of memory and possibly inconveniencing others, so I can shut down my ...
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0answers
37 views

Possible slab memory leak related to bio and btrfs?

I'm currently running a rebuild on a btrfs NAS (~20TB) that had a drive failure. It's going to take a few days. My problem is about once every 24 hours the RAM filled up and the kernel starts killing ...
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1answer
35 views

What does a “Synchronous” type detail mean in dmidecode?

I'm curious if my 2 DIMMs are running dual-channel or not and use: dmidecode -t 17 ... Type Detail: Synchronous ... What does a "Synchronous" type detail mean? Dual-channel?
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2answers
54 views

How to determine which files are necessary in /bin, /lib, /var, etc.?

I'm currently trying to get an image working for a network boot using somebody else's file contents. The previous images I made keeping all original files present were way too big, so I need to shrink ...
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1answer
36 views

Limit CPU and Memory usage for C, Java programs at system level

I am building an online code editor for C and Java. Chances are users will write infinite loops. Is there any way I can limit the cpu and memory utilization of these processes at system level settings ...
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2answers
32 views

U-Boot shell - show memory usage (like Linux free command)

Is there any way of displaying memory usage from U-Boot? I mean operation memory - like sdram - not mmc.. Ideally from shell but I can be happy also with C command as I compile U-Boot myself.
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1answer
31 views

How to obtain counters for swap-in/swap-out on Linux?

I'm trying to obtain counters for swap-in/swap-out activity on CentOS 6. The intention is to feed raw data into RRDtool to generate graphs, and use it to generate alerts. I've had a look at common ...
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4answers
2k views

Get separate used memory info from free -m comand

As a output of free -m command I got following. total used free shared buffers cached Mem: 2496 2260 236 0 5 438 -/+ ...
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8answers
6k views

cron Vs. sleep - which is the better one in terms of efficient cpu/memory utilization?

The Case: I need to run some commands/script at certain intervals of time and for this I have two options: set up a cron-job implement a loop with sleep in the script itself. Question: Which is ...
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0answers
481 views

Debian - Apache 2.2 & mod_php - memory usage

I have a memory problem with my servers (Debian 6.0) where is installed Apache httpd 2.2, mod_php and APC. Actually it seems that httpd allocate all available memory (4GB) when is waiting too much ...
4
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2answers
1k views

Limiting the Size of Apache HTTPD Memory Footprint

I have a web server running Cent OS 5 with Apache. I have over 1GB of Ram and the MaxSpareServers set to 15. This would be fine under most situations, but for some reason my httpd processes are ...
5
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1answer
11k views

httpd memory usage

Having some problems with httpd (Apache/2.2.29) memory usage. Over time, memory usage in the httpd processes creep up until it's eventually at 100%. Last time I restarted httpd was about 24 hours ...
111
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12answers
62k views

How to fill 90% of the free memory?

I want to do some low-resources testing and for that I need to have 90% of the free memory full. How can I do this on a *nix system?
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2answers
2k views

How to limit the total resources (memory) of a process and its children

There are plenty of questions and answers about constraining the resources of a single process, e.g. RLIMIT_AS can be used to constrain the maximum memory allocated by a process that can be seen as ...