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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Is there anything in RHEL 6.5 that would affect I/O speed for something <24K vs >24K?

Generally, transactions for my app of setting and getting data internally are measured in a couple of millis. However, over 24K in size, that time can jump to just over 100 millis. Is there anything ...
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2k views

Defragging RAM / OOM failure

This question is fairly lengthy, so I'll ask the questions at the top and then go through my method of coming to the questions: Did (Busybox based) rm not execute because there wasn't enough ...
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1answer
106 views

Fastest and Safest way to increase Swap Space on Scientific Linux

Memory Swap Ratio Company System Today, a monitoring system indicated that one of the systems in the company has run out of memory. Executing htop on this system indicated that the Memory was nearly ...
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2answers
158 views

Why does Linux only see 3832MB of my 4096MB of RAM?

I am setting up a lot of 64-bit RedHat VMs (VMware vSphere) for our development department in my company. Most of them start with 4096MB of RAM, but Linux only seems to recognize 3832MB. Can anyone ...
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1answer
124 views

How to prevent certain memory location to be accessed [duplicate]

I have 2 corrupted RAM module, on offset: 46xx MB and 13xxx MB (from memtest on boot) How to prevent Linux to access/alloc/read/write into those offset? Here's the result of memtester on ~1000 MB to ...
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1answer
57 views

How can I tell if lack of memory is causing these crashes?

I have a tornado web server running a flask application that connects to a postgres 9.3 database on an ubuntu 12.04 box. The application has been crashing intermittently and I am trying to understand ...
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1answer
620 views

Real vs Actual memory in Xymon/Hobbit

What is the difference between real and actual memory usage in xymon ?
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2answers
173 views

What are the positions in `free` called?

I am trying to compare the output of free with the output of sar -r: # sar -r 12:00:01 AM kbmemfree kbmemused %memused kbbuffers kbcached kbcommit %commit 12:10:01 AM 629756 65293976 ...
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3answers
5k views

What does the vm.swappiness parameter really control?

Per the kernel documentation: This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase aggressiveness, lower values decrease the amount of swap. ...
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4answers
1k 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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58 views

Why does Android crash when stressed on Memory where as GNU-Linux keeps running?

I have two devices, an Android phone with an eGlibC stack running side by side with Bionic, and an old HP tower with Debian. My HP tower has 512 MB of RAM. My phone has 2GB of RAM. I run top on ...
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4answers
188 views

What is using memory? [closed]

According to htop and free, the machine I'm looking at is currently at 6631 / 11907 MB of RAM. That's more or less half of the RAM available. However when I sort top or htop by MEM%, the most memory ...
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2answers
1k views

How does stack allocation work in Linux?

Does the OS reserve the fixed amount of valid virtual space for stack or something else? Am I able to produce a stack overflow just by using big local variables? I've wrote a small C program to test ...
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2answers
47 views

How to monitor Memory utilization of the single process?

How to monitor Memory and CPU usage of the single process by program/executable name(not PID);
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3answers
4k 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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1answer
1k views

Maximum memory usable by a 32 bit RHEL 6 system

I have installed a 32 bit RHEL OS on a 64 bit system. From the wiki page of PAE: The Linux kernel includes full PAE mode support starting with version 2.3.23, with Linus Torvalds mentioning ...
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2answers
79 views

How to format the output of free/sar/such commands?

I need to get some specific columns from the output of free command. The way I'm following doesn't seem good, could anyone please suggest me a better way? bash-3.2$ free -gotsi total ...
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2answers
109 views

centos5 maximum memory setting for all users

I'm using Centos5 for operating server and the machine has limited memory. There are many users using the server and some of them are running programs which use a lot of RAM. When I check the used ...
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1answer
330 views

How is 32bit Linux virtual memory structured in relation to PCIe Base Address Registers

I'm working on a Linux system (32 bit, 4GB RAM) and found some contradictory information about memory addressing in Linux. Am I right with this: Only virtual memory has the differentiation between ...
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2answers
194 views

Linux memory usage?

We have 1TB of memory on a server which hosts an SAP application. When the app is running the memory usage shown in top is around 700GB. When the app is stopped the memory usage shown in top comes ...
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0answers
721 views

How extended (4MB) and regular (4KB) paging coexist?

On x86 architecture, "Extended paging" allows page frames (physical memory) to be 4 MB instead of 4 KB. The book "Understanding the Linux Kernel, 3rd" at chapter 2 "Memory Addressing", sub-chapter ...
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9answers
11k views

Why can't Vim open a 100 MB text file when I have 16 GB RAM?

I have a 100MB MySQL database backup file and I have trouble to open it in Vim on my Linux box that has 16G of RAM. Vim just hangs (at least unusable). This is something I don't understand. I have 16 ...
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2answers
41 views

How much memory is lost on startup

I was wondering the following: As I start my computer and Xubuntu, it starts many programs before the login screen. Is it possible to measure by Valgrind the total number of lost bytes during startup? ...
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1answer
1k views

How to reduce chrome's virtual memory usage?

I am running a Debian Jessie and having memory issues when using Google Chrome I tried disabling extensions, disabling cache, flushing the cache, and disabling the web 3d rendering, but nothing ...
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74 views

Cgroups - memory subsystem

I want to set the memory.limit_in_bytes parameter for a control group and disable OOM, so processes freeze when the limit is reached. But i want to change that limit dynamically, if there is more ...
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1answer
2k views

What is equivalent to Mac's purge in Linux?

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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1answer
3k views

What do the different memory counters in FreeBSD mean?

top tells me: last pid: 64807; load averages: 0.99, 0.97, 0.92 up 189+04:47:22 09:16:17 45 processes: 1 running, 44 sleeping CPU: 0.4% user, 0.0% nice, ...
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1answer
982 views

How to figure out memory leaks? [closed]

I'm running Ubuntu 14.04 on Digitalocean to host my blog. I'm using HHVM + nginx + MySQL. Every few hours (~12h), there's no more RAM left and nginx throws an 502 error. I check the memory usage for ...
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1answer
4k views

The meaning of output of pmap

I wrote main.c in Linux: int main() { while (1){} } When I compile and start it, I can pmap it: # pmap 28578 28578: ./a.out 0000000000400000 4K r-x-- /root/a.out 0000000000600000 4K ...
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2answers
4k views

Will Linux start killing my processes without asking me if memory gets short?

I was running a shell script with commands to run several memory-intensive programs (2-5 GB) back-to-back. When I went back to check on the progress of my script I was surprised to discover that some ...
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2answers
4k 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
658 views

How to mount a dd-image which was created via fmem (memory dump tool)

I'm quite new to Linux. I've used the tool fmem for creating a memory dump dd-file. That works fine. But how can I access this image? I've tried it with mount but it says I have to specify a ...
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2answers
815 views

Out of Swap - What happens?

On my debian VM machine with 512MB RAM and 348MB Swap, what will happen if i open a 1GB file in an editor and get out of memory? Will it crash the system? Or if not, how will linux handle this? ...
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1answer
8k 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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4answers
5k views

Shell command to read device registers?

On a single-board computer running Linux, is there a way to read the contents of the device configuration registers that control hardware? I think it would be a wrapper for inw(), more or less. I'm ...
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2answers
112 views

Swap to RAM, or not

Having a 32-bit system with 4G RAM and 7G swap. Linux 3.5.0-49-generic i686. From time to time the memory bank is filled up and everything lags down. In 99% of the cases it is Chrome using vast ...
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2answers
1k views

Does BIOS read directly the bootloader or load it into RAM?

I'm trying to understand the very first steps of the boot process. The CPU read the BIOS It reads a fixed address instruction It will jump to the first BIOS instructions address It will execute ...
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2answers
815 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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1answer
199 views

Virtual Memory Usage Exceeding Physical Drive Space

I have a machine running Ubuntu on Amazon EC2. The machine has a 43 Gb root drive and 30 Gb of RAM. I am running a processor and memory intensive process and I've noticed that it sometimes stalls for ...
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1answer
270 views

xentop gives static info about memory usage

I am using CentOS 6.5 and Xen 4.2.4-30 xentop does not change MEM(%) at all. NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%) VCPUS NETS NETTX(k) NETRX(k) VBDS VBD_OO ...
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1answer
6k views

What does the Virtual kernel Memory Layout in dmesg imply?

While going through the "Output of dmesg" I could see a list of values which i am not able to understand properly. Memory: 2047804k/2086248k available (3179k kernel code, 37232k reserved, 1935k ...
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1answer
68 views

Memory consumption of a script

Is there way to check the memory (physical & virtual) consumption of a script, of course in the moment of its execution. Calculating the used memory minus the used memory before and after the ...
4
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1answer
573 views

Does 'ulimit -m' not work on (modern) Linux?

This article claims that the -m flag to ulimit does nothing in modern Linux. I can find nothing else to corroborate this claim. Is it accurate? You may try to limit the memory usage of a process ...
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3answers
7k 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
160 views

How to extract running Apache configuration from core dump?

Apache is loading the configuration from files into its memory. If the config files are changing the Apache process won't activate it until a reload/restart happens. Now I have to debug the current ...
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1answer
447 views

Fastest `uniq` tool in linux

I have large text file (1.5 G), I want to know what the fastest and more reliable tool in linux is. I usualy use: awk '!x[$0]++' file.txt But when I use htop command I see my memory usage is ...
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Debug out-of-memory with /var/log/messages

The following report is thrown in my messages log: kernel: Out of memory: Kill process 9163 (mysqld) score 511 or sacrifice child kernel: Killed process 9163, UID 27, (mysqld) total-vm:2457368kB, ...
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2answers
166 views

cannot find what has used all the memory

The server has about 24GB memory. By running free -g I find the memory is used up total used free shared buffers cached Mem: 23 23 0 ...
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1answer
2k views

What would happen if the amount of free memory (vm.min_free_kbytes) was too low?

I came across the following parameter in kernel settings (in sysctl): vm.min_free_kbytes This is the amount of free memory (RAM) that's always free no matter what. In my case, I have only 1 GiB of ...
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3k views

how is page size determined in virtual address space?

Linux uses a virtual memory system where all of the addresses are virtual addresses and not physical addresses. These virtual addresses are converted into physical addresses by the processor. To ...