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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14
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5answers
3k views

Read the stack of another process?

I'm trying to read a child process's stack but with no luck. I know it is possible using ptrace, but ptrace's interface allows you to read only one word at a time, and I'm trying to scan a larger ...
1
vote
1answer
43 views

how do I know if and why linux is killing my processes?

I'm working on one of amazon's linux distros (4.4.11-23.53.amzn1.x86_64). (1gb ram)on that instance I am running node.js with the forever module. (It makes sure to restart the node.js process if it ...
0
votes
0answers
37 views

How to Study Effect of zram on Memory Size and Paging?

Situation: to study the effect of zram's virtual memory compression (wiki) on memory's size and its speed; when swap is not on HDD/SSD; use zswap if you want to have swap on HDD/SSD Motivation: I ...
1
vote
0answers
23 views

“swap cache” of vmstat vs. “SwapCached” of /proc/meminfo

On my Fedora 24, I executed two commands to examine the memory information, however, I got two different results about swap cache's size. The first command is as follows: [root@localhost ~]# vmstat -...
0
votes
1answer
1k 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 ...
21
votes
2answers
32k views

How to create a user with limited RAM usage?

So I have 4 GB RAM + 4GB swap. I want to create a user with limited ram and swap: 3 GB RAM and 1 GB swap. Is such thing possible? Is it possible to start applications with limited RAM and swap ...
2
votes
0answers
44 views

Less RAM Aailable than installed on Centos 7

I can't seem to figure out why do I have less RAM usable than installed. I am running 64bit Centos 7 with 1 RAM module of 4096MB on a Lenovo x230. Some information from the machine in question: $ ...
0
votes
0answers
14 views

Kernel module crashes when reading memory [migrated]

If I know the physical memory of data, because it was placed there by a memory mapped peripheral, how do I access it in a kernel module? My first instinct is to make a pointer int * addr; and ...
0
votes
0answers
33 views

Is there a more efficient way of defragmenting Linux memory other than rebooting?

I am running Gentoo Linux with kernel 4.4.8-hardened-r1, QEMU-KVM version 2.5.1 and 3227 MB of system-visible RAM (without considering RAM taken by BIOS and my AMD APU's graphics). I have a VM that ...
6
votes
2answers
3k views

How can I tell what memory RAM address range is being used by uboot?

I am in uboot and was wondering, how could I tell what RAM address range is being used by uboot. uboot needs memory to run so it might be using some of the RAM. I want to avoid modifying those RAM ...
2
votes
1answer
26 views

performance comparison of multiple commands excutions

I've got three different programs written in three different languages, and I'm trying to compare their performance in terms of runtime, and memory consumption. What I'm looking for is some command ...
4
votes
0answers
42 views

Why does /proc/*/status not account for all swap used on a system?

I have a system that has been swapping recently and am unable to account for all swap that is shown as in use by tools like free or top. Specifically, I can account for 19GB of 28GB swap used (...
15
votes
2answers
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 ...
5
votes
0answers
38 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 ...
0
votes
0answers
26 views

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 ...
5
votes
2answers
75 views

Where the remaining memory of vm.overcommit_ratio goes?

If I disable memory overcommit by setting vm.overcommit_memory to 2, by default the system will allow to allocate the memory up to the dimension of swap + 50% of physical memory, as explained here. I ...
79
votes
6answers
101k views

Limit memory usage for a single Linux process

I'm running pdftoppm to convert a user-provided PDF into a 300DPI image. This works great, except if the user provides an PDF with a very large page size. pdftoppm will allocate enough memory to ...
4
votes
2answers
6k views

How to measure on Linux the peak memory of an application after has ended

How do I measure the peak memory of an application running on Linux? I run this app in batch so I cannot use RSS since, it reports the current memory. I need the peak memory that the application has ...
0
votes
0answers
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. ...
0
votes
0answers
33 views

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 ...
4
votes
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 ...
8
votes
1answer
295 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 ...
1
vote
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 ...
1
vote
1answer
36 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 ...
8
votes
5answers
22k 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 ...
5
votes
2answers
22k 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. ...
11
votes
1answer
590 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?
7
votes
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: ...
0
votes
0answers
13 views

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?? ...
8
votes
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 ...
0
votes
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....
16
votes
4answers
997 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 ...
2
votes
0answers
45 views

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 ...
1
vote
2answers
37 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'...
3
votes
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 ...
5
votes
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 ...
13
votes
2answers
5k 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
votes
1answer
679 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" >>...
4
votes
3answers
115 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 ...
3
votes
4answers
22k 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
3
votes
0answers
28 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....
1
vote
0answers
109 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 ...
7
votes
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 ...
1
vote
1answer
31 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 ...
1
vote
1answer
38 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 ...
1
vote
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 ...
1
vote
1answer
36 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"?
3
votes
0answers
142 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, ...
0
votes
0answers
67 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 ...
3
votes
2answers
46 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 ...