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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are daemon tmpfs executables copied unencrypted to memory upon execution? (prevent if so?)

When a daemon is executed, is the executable copied to memory? If so, can it be copied encrypted? If not, is there a way to prevent the executable from being copied to memory? The executable is ...
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141 views

How to make sure, that certain functionality (like Alt+Ctrl+F1 switching into tty) is available in havily swapping system?

At the moment, when I accidentally launch application that eats a lot of memory (that causes system to heavily swap), the system become so unresponsive (waiting hours just to see the mouse move/or ...
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2answers
196 views

process memory usage

What is usually meant by the phrase process memory usage, what does this actually mean, i.e. what does this memory consist of? And what column does it correspond in ps aux output, RSS or VSZ?
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1answer
434 views

Measurement of free ram through /proc/meminfo with ramdisk (initrd)

I am booting a disk image via PXE, it is a full system on an initrd ramdisk. I would like to measure the actual free memory of the system (not including buffers and file system caching). I was told ...
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1answer
2k views

Redhat find process memory usage [duplicate]

When I cat /proc/meminfo I see: MemTotal: 1048576 kB MemFree: 11136 kB Buffers: 0 kB Cached: 0 kB SwapCached: 0 kB Active: 0 kB Inactive: ...
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Where is the environment string actual stored?

But when we first time we adding a new name,we have to call malloc to obtain >room for a new list of pointers. We copy the old environment list to this new area and store a pointer to the ...
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3k views

How to blacklist a correct bad RAM sector according to MemTest86+ error indication?

MemTest86+ (the version included with Ubuntu 13.04) says Failing address: 002f796c48 - 759.5 MB What should I specify in the memmap kernel parameter to bypass this area? I've tried running ...
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3answers
531 views

After researching, still confused about monitoring RAM usage

I went through this article, which explains various methods for checking your RAM usage. However, I can't reconcile the different methods and don't know which one is correct. When I first login, I'm ...
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1answer
6k views

How to find Heap memory of a running process? [duplicate]

I would Like to know how to find the heap captured of a process which is running in the background? Is there any command by which you can find the process heap memory and here the process is still ...
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1answer
128 views

“Acpi-State” in slabtop's output gets increased — what is it? Is it a bug?

Since boot it gets increased occupying even more RAM than anything else: Active / Total Objects (% used) : 680608 / 719176 (94.6%) Active / Total Slabs (% used) : 17390 / 17390 (100.0%) ...
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1answer
153 views

How to measure the clock pulse of my computer manually?

My PC has two processors, and I know that each one runs at 1.86 GHz. I have just read about clock cycles and I only have a (very) rough understanding, so I apologize beforehand if my question is so ...
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1answer
133 views

Looking for /procfs documentation, describing values and units of measurement

Surprisingly, comprehensive documentation for /procfs is hard to find. For my specific question, I am looking at: cat /proc/1/statm (let's use pid=1 because it seems to be always there). I just ran ...
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3answers
625 views

Linux / JVM - OutOfMemoryError: unable to create new native thread

I have a memory problem with a Linux server (CentOS). It is a VM. Below is the context. It has 70Gb of RAM. There are 2 tomcat running on it. One tomcat is given a heap of 13Gb and the other one a ...
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1answer
387 views

is free command displaying all physical memory or there is some RAM reserved and hidden?

I am supposed to have 512MB of ram on my VM, however I see 495mb of total ram when I do free command. I would like to know if in case my system really had "precisely" 512MB of physical ram, if in ...
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1answer
221 views

What's using all of the memory in my VM? It's not the disk cache

I have an issue where when I try to build a really large project, my machine starts swapping (several GB) even though there's plenty of memory (14 GB in fact). When I run free, it shows that it's not ...
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2answers
821 views

Linux: Total swap used = swap used by processes +?

So, I'm trying to do some investigation on where does swap use come from in a system with high swap usage: # free total used free shared buffers cached Mem: ...
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“/sbin/yast: fork: Cannot allocate memory” on openSUSE 10.1

I guess I'll come across as a total newbie for asking this, but I get the above message right after starting an ssh session. The reason I opened the ssh session was that I came across a 500 internal ...
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0answers
109 views

RES memory more than initial and maximum memory for java

We have a java application running on Centos 6.4 what we notice is that the RES is around 370m which is more then the allocated max that is 256m. Does this signify that we the application is leaking? ...
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3answers
2k views

Human readable system memory reading crom CLI?

On OS X, I get a nice human readable system memory reading like so: printf -v system_memory \ "$(system_profiler SPHardwareDataType \ | awk -F ': ' '/^ +Memory: /{print $2}')" ...
4
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1answer
815 views

Which parts of an ELF executable get loaded into memory, and where?

What I already know: An ELF executable has a number of sections, obviously the .text and .data sections get loaded into memory as these are the main parts of the program. But for a program to work, ...
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1answer
972 views

Limit CPU and memory usage for PHP-FPM and Nginx processes in CentOS

I want to limit CPU and memory usage for PHP-FPM and Nginx processes in CentOS. I came across following tools cpulimit cggroups memory resource locater which will more efficient and how can I ...
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297 views

Where is the virtual memory stored on hard drive?

If a process wants to access a memory address that is not in physical memory, the OS outsources a page frame from physical memory to the hard drive for later use. Where on the hard drive is this data ...
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417 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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1answer
176 views

What information exactly is in the access control bits of a page table?

I'm currently learning for an exam in operating systems. This includes learning some basics about page tables, which lead me to the question Why using hierarchical page tables? which mentions that ...
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1answer
1k views

How to monitor RAM ECC errors on Ivy Bridge Xeon E3 processor in Linux?

How can I monitor if there are any errors in RAM that get corrected by ECC? The processor is an Intel Xeon (Ivy Bridge) processor, the operating system is Scientific Linux 6.3. On a previous system I ...
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How can i free up memory / manage memory on a linux box?

I am running two Ubuntu 12.04 servers (no GUI / desktop) using canonical's cloud images on Amazon EC2. One is a micro with 613MB of RAM and one is a medium with 3.75GB of RAM. I only have opscode's ...
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1answer
99 views

Not using specific memory regions due to errors

I have just installed some new RAM (2x1GB, 667, sticks from 2x512MB, 533, sticks) into an old system (perfectly valid), and all was working fine, until now. I have been having some issues when the ...
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2answers
135 views

Where is the frame.h located in modern Linux implementations? (ubuntu specifically)

A book I am reading refers to an include file that shows how a stack frame looks on one's UNIX system. In particular: /usr/include/sys/frame.h I am having trouble finding the modern equivalent. ...
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1answer
794 views

Invoking memory compaction on linux 2.6.35 kernels and beyond

This LWN article about memory compaction indicates that memory compaction can be invoked in the linux kernel by Writing a node number to /proc/sys/vm/compact_node, causing compaction to happen on ...
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3answers
4k 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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2answers
202 views

find total ram memory and swap memory

I need to write a script to find total memory and total swap of several linux server (2000+). I have one trusted server from where I can login to all these 2000 servers without a password. When I run ...
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1answer
708 views

Huge page and performance improvemnt

How can using huge page improve performance? I have read that huge pages improve performance by reducing TLB lookups and reducing the size of the page table. Can someone tell me how this helps with ...
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How can I dump the full system memory?

After starting VirtualBox, the computer became sluggish and then hung completely due to OOM. Usually, OOM should be starting killing processes in order to free up some space, but this did not happen ...
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1answer
2k views

htop reporting much higher memory usage than free or top

The following three outputs were taken essentially simultaneously: top: top - 02:54:36 up 2 days, 13:50, 3 users, load average: 0.05, 0.05, 0.09 Tasks: 181 total, 1 running, 179 sleeping, 0 ...
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3answers
2k views

kswapd0 takes 99% to 100% CPU in RHEL 6.3

I have 5 systems on which I have just installed RHEL6. System configuration is CPU-i7 HDD-500 GB RAM-2 GB Swap- 4 GB I have installed the same software's and all the configuration as per ...
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2answers
523 views

How to solve this memory issue gracefully?

I have a standard Linux (Debian testing) laptop, with a swap partition. I do a lot of experiments with it. Some of them are really memory hungry and the way Linux behaves by default is an issue for ...
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2answers
451 views

Memory management, bias to swapping

I was having 768 MB RAM. In a general day MySQL was using 100-180 mb of RAM and MySQL was swapping 80-120 mb. I was having 50-60 mb free RAM. So I thought I should upgrade. Then I upgraded my RAM ...
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148 views

Why message queues were not being used for any application?

In my Linux machine, when i run 'ipcs' command, I have the below information listed srinivas@srinivas-G41MT-S2:~$ ipcs -a ------ Shared Memory Segments -------- key shmid owner ...
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1answer
563 views

Which processes swaps memory

I can see swap's total, used, free etc. sizes from top command. But I can't figure out which process uses swap, is it possible to find out swap memory by process? I'm running CentOS 6.3.
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2answers
977 views

What is “automatic stack expansion”?

getrlimit(2) has the following definition in the man pages: RLIMIT_AS The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2) and ...
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2answers
264 views

Does Linux have ways to cache IO with memory

My server has a large amount of memory. However, the amount of IO (each of which is small) is very high. Is there a way to make a virtual drive out of portion of the memory? I realize I can also use ...
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2answers
981 views

What is “kernel dynamic memory” as reported by smem?

While diagnosing low memory problems in my desktop machine (details at U&L) I've noticed that my noncache "kernel dynamic memory" is big: # smem -twk Area Used ...
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1answer
58 views

How might I detect memory errors if I do not have root or physical access to a Linux system?

The background to my question is as follows. I currently rent a virtual private server from a major hosting company, which I use to run a minecraft server. I have a suspicion that there may be bad ...
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2answers
842 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
1k 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. ...
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Limit disk buffer usage in SLES 11SP2 to allow more efficient memory overcommit on esxi host

When running VMs on an ESXi host, you can overcommit the memory. Example: host == 20GB physical RAM The amount of RAM allocated to each VM is VM1 == 10gb VM2 == 10gb VM3 == 10gb VM4 == 10gb The ...
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Why is the theoretical RAM limit for RHEL 6 128 TB and how is this determined?

I'm studying for RHCSA and am confused by a statement I came across in some training material: There is no practical maximum RAM, as theoretically, you could run 128 TB of RAM on RHEL 6. But ...
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335 views

Where does the Linux kernel reside in memory ?

From some book I have, I have in my notes that the Linux kernel resides at 0xc00000000 on 32-bit systems, and is mapped into user space for performance reasons. Is this accurate ? How can I verify ...
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2answers
2k views

What a 64 bit Linux can do that 32 bit linux can't?

I ordered a server from fdcserver. Then I realized that, unless changed, fdcserver actually provides 32 bit operating as default. I logged in using SSH, typed uname -m, and to my horror I saw that I ...
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2answers
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Why buffers equals to used memory?

I'm using Ubuntu 11.10, virtualized by OpenVZ. That output of free -m shows that buffers is always equal to used. total used free shared buffers cached Mem: ...