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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upstart jobs - privileged vs unprivileged

On one of my VMs, some upstart jobs were failing, and when I checked df, showed that I had run out of disk-space (Use% was 100 on /dev/sda1). What I did not get is: the jobs which were running with ...
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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
64 views

Why is IO so high when almost out of memory

On my work laptop with an SSD and no swap, I sometimes run out of memory when running RAM-expensive applications (virtual machine, etc). When that happens, the system becomes slow (expected) but what ...
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196 views

Memory usage of a given process (using Linux proc filesystem)

I want to know which files from /proc directory and which fields of these files I need to calculate the memory usage of a given pid. I've been using the "stat" file and the "vsize" parameter that is ...
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3answers
562 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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Mathematical connection between SZ RSS and VSZ in ps o/p?

I wanted to know what mathematical connection is there between the SZ, RSS and VSZ output in ps output e.g. ps -p 2363 -o sz,rss,vsz
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191 views

How do see the memory used by a program in ubuntu?

How can I see the raw memory data used by an application ? Like , suppose I have a file name something.sh . Now I run the command ./something.sh , and then I want see all the data its accessing in ram ...
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18 views

How to troubleshoot High VIRT and RES memory on a Standby Server

We currently run TIBCO EMS on our RHEL6 servers, it is Active-Passive setup, for some reason we are seeing a really high VIRT and RES usage by the standby instance (approx 198GB). The application ...
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28 views

tstime and memory usage

So I am interested in measuring the high-water memory usage of a process. I would love to be able to use tstime but am having troubles figuring it out. Does it work in Unix? When I go to ...
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2answers
345 views

Memory usage of an infinitely looping shell script

So, I have a shell script for updating a MySQL database that looks something like this: #!/bin/sh mysql -h "localhost" -u "root" "-p********" "database" < "update.sql" sleep 5 sh $0 It sleeps ...
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2answers
293 views

Physical Address Extension - how do virtual addresses work?

I'm running Debian Linux. uname -m says i686 which means 32-bit architecture machine with pae flag enabled. getconf LONG_BIT is 32. Installed RAM capacity is 6GB. My /proc/cpuinfo has an entry ...
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57 views

Why process is killed while a lot of memory is free?

I am running a python script in ipython. This script will take about 8GB RAM. The system has more than 80 GB free RAM but the swap is nearly 0. My script was killed after it runned for a while. I want ...
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1answer
39 views

Can I trust in memory information of dmicode?

I want to buy 16gb memory for my notebook. I ran dmicode and found this information: Handle 0x0005, DMI type 5, 20 bytes Memory Controller Information Error Detecting Method: None ...
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38 views

/proc filesystem - getting useful information

I'm trying to understand the values in /proc/PID/status. I want to calculate cpu% & mem% used by PID, similar to top bash command. For Memory percentage usage I can do the following (correct me ...
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1answer
133 views

Resource (CPU time and memory) limitation and termination of a process upon violation in Linux

The problem: Given a process, limit the resources it and its child-processes can use. I.e. set CPU time and virtual memory quotas. When the process group exceeds one of the limits, terminate it, ...
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1answer
125 views

What does Linux spend memory on other than userland, caches and slab?

I have a system with 1 GB of physical RAM. Right now, free shows the following memory usage: total used free shared buffers cached Mem: 1026360 863660 ...
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49 views

Which process wrote to which memory address? [closed]

Recently, I've been seeing a wide variety of memory-related crashes at work (C++ applications on Ubuntu 14.04). Our applications use a properietary third party library to interface with real time data ...
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1answer
148 views

How to find the page size of physical memories from userspace?

I want to understand the page size, sector size, block size (if applicable) of a usb flash drive. Is there a way for me to inspect those with Ubuntu? mount /dev/sda1 /mnt ? umount /dev/sda1 Edit ...
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94 views

Is High Virtual Memory usage a problem or may cause problems?

In our server, we have a python based code that listen ports. The amount of Virtual Memory it uses is increased greatly with time Like: USER PID %CPU %MEM VSZ RSS TTY STAT ...
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12answers
17k views

Do I need swap space if I have more than enough amount of RAM?

From what I understand, the purpose of a swap partition in Linux is to free up some "not as frequently accessed" information from RAM and move it to a specific partition on your harddrive (at the cost ...
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1answer
132 views

How do I forbid access to physical memory in Linux?

I'm on an embedded system (Zynq from Xilinx. It uses ARMv7, Cortex-A9), and running Linux. I need to ensure that no access to a certain physical memory range is ever made, either accidentally by the ...
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82 views

What is kswapd_low_wmark_hit_quickly from /proc/vmstat

What does this parameter mean? # cat /proc/vmstat | grep low kswapd_low_wmark_hit_quickly 2
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30 views

Page Fault Frequency Algorithm - Compute number of frames and mean resident set

I'm reading about Page Fault Frequency algorithm but I don't understand how can I compute the number of frames. For example I have my reference string: 112233444412412214432255543 and control ...
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1answer
77 views

Substantial portion of memory used is not accounted for by user processes

I recently installed a copy of Ubuntu Server 14.04.2 LTS on a cluster. All appears to be working fine, but a large portion (around half) of our total available RAM is being used. I.e., when I run ...
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276 views

Does anyone actually use and benefit from transparent huge pages?

I've been struggling with transparent huge pages performance issues of late, and noticed many database systems recommend turning it off. I am talking Oracle, Postgresql, MySQL, Cassandra, NuoDB, ...
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2answers
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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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90 views

How to determine the memory usage of a single process?

There a few helpful scripts out there, which give some useful information. But I would like to calculate those values myself. I am interested in values like USS and PSS. I already had my first attempt ...
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2answers
110 views

Sum the memory usages of all the processes of a program?

How can we sum the memory usages of all the processes of a program? For example, I have opened many Chrome tabs for webpages, and each tab runs a different process. How can I get the total sum of ...
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1answer
295 views

Process Being Killed due to low swap

I'm running a python (2.7) script on mac osx yosemite. The script is fairly computationally intensive, certainly bumping up against my machine's RAM limitations. The computer crashes and restarts ...
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2answers
154 views

What unit is used for the memory values from top command in Linux?

I have the following snippet shown as my top command output. One real quick question here being, the values of Mem are shown in what granularity? Are they the number of bytes? Mem: 8191488k total, ...
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302 views

Linux Mint 64 bit eating ram

I have a Mint 17.1 install. It has 2x2Gb memory sticks. I have verified this with sudo dmidecode --type memory. My problem is that I don't see all the memory I expect.I would expect 4194304 kB. (i.e. ...
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40 views

Memory utiization

I use free -m to check memory status. In this pic we see total used & memory. I want the result in %. Like Used memory - total memory x by 100. And whenever I want to check the memory status, it ...
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2k views

How to calculate the memory consumed by a “C” program in linux

I have written two C programmes one is using function pointer, and the other without function pointer. Now i want to know the memory consumed by the two programmes , to see how memory can ...
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326 views

Java process gets killed frequently by OOM - Killer on upgraded hardware

I am running solr on an Ubuntu server along with 4 other java processes. Current index size is 30 GB. My solr process gets killed frequently in few hours. It clearly mentions that its an OOM killer. I ...
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828 views

When a process forks is its virtual or resident memory copied?

The standard way of making new processes in Linux is that the memory footprint of (parent) the parent process is copied and that becomes the environment of the child process until execv is called. ...
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1answer
133 views

/dev/mapper/vg00-var maxing out

Over the past few years we have had multiple Linux servers have the same problem time and time again: our /dev/mapper/vg00-var folder maxes out at 100%, which means all sites on the server die. We ...
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2answers
279 views

CRON Job To Execute Command On Low Memory

I have a situation where I may need to execute an SAP command line tool hdbsql when memory gets too low (to help clean out the HANA table cache). I'm not well versed in Unix/Linux, and was wondering ...
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185 views

Kill the process and restart server when memory is exceeded - bash and cron

I have a site on webfaction, using django and python. However, I have problem with memory. The problem arises, because I use external library, that can run forever (consuming much time and memory). ...
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How to recover data after memory module errors [duplicate]

My linux PC has suffered the occasional application crash, desktop crash, and kernal panic over the last few months. I also started noticing error dialogs on login, and some parts of the desktop do ...
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1answer
164 views

Linux doesn't drop FS Caches. Instead Memory starts Swapping

I'm quite confused about this behaviour of linux memory caching. total used free shared buffers cached Mem: 15953 14188 1765 64 ...
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2answers
1k views

How to enable swap accounting for memory cgroup in Archlinux?

On my Archlinux box I want to limit some applications to a smaller amount of memory using cgroups. Since I use swap, I need to account memory+swap. How can I enable swap accounting?
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2answers
260 views

What proportion of memory does the Linux kernel use of the installed RAM?

I'm developing a compute cluster and I'm trying to determine the maximum amount of RAM I can give to a single process. On a machine with 16GB of ram, the answer is that I can allocate (and touch) ...
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1answer
853 views

what does mean by HardwareCorrupted, DirectMap4k, DirectMap2M fields in “/proc/meminfo” file of Linux?

I am looking for description of following terms: HardwareCorrupted, DirectMap4k, DirectMap2M fields in "/proc/meminfo" file of Linux. I could find the following description for the fields from ...
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4answers
1k views

Memory consumption Fail2Ban CentOS

Fail2Ban is using a huge amount of memory on my system (1.2 GB). There are several articles which describe how to reduce it. Below is an example for Debian. append the 1ulimit1 command to ...
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1answer
51 views

Who are the Linux Memory “subsystem” developers?

After an hour of googling, I still cannot find Linux Memory subsystem developers contact e-mail. Question: Where is the webpage that shows who develops the Linux kernel, specifically the Memory ...
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1answer
866 views

git Fatal: Out of memory, malloc failed on branch push

I know this has been asked a lot but I did not manage to get any solution to solve my problem. My coworker assigned me on a new project. The application is hosted on test Debian server with git ...
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100 views

What is kernel memory and user memory? (question about the term kernel page and the page cache)

Today, I have read through some documents about file system (http://tekrants.me/2014/07/14/linux-file-system-write/). And the term kernel page is mentioned several times in this article. I am now ...
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245 views

How to read the output of the show-memory-usage SysRq?

I couldn’t find any (recent) documentation on reading the output of the show-memory-usage SysRq (Alt+SysRq+m). So what can one learn from looking at it? Here is an example output form my box (Kernel ...
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2answers
28 views

Utility which gives line from /proc/id/maps by specific address

Is there an utility that gives me specific line from /proc/id/maps when given specific address from this process? For example when given 0x7fb4a84f6008 it returns: 7fb4a84f6000-7fb4a84fd000 r-xp ...
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0answers
33 views

Which parts of Memory can Swap Support

For this question, "swap" does not include RAM and only refers to the configured space on the disk. According to, http://www.ualberta.ca/CNS/RESEARCH/LinuxClusters/mem.html, a program's memory usage ...