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 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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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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3answers
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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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12answers
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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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How can Profile/Benchmark ram performance?

Effectively I would like to know if my memory hardware it a bottleneck of my system performance. I am dealing with really old hardware (late 2000), mind you. If there is room for improvement I would ...
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1answer
38 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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2answers
4k views

How to reduce ClamAV memory usage?

I'm running a Ubuntu based web server (Apache, MySQL) on a 512MB VPS. This is more than sufficient for the website it is running (small forum). As I wanted to add some protection against viruses I ...
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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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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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573 views

Does sync command remove the dirty cache in the memory?

I am aware that sync command flushes the dirty cache into disk. I have run free command first, then sync, and then free again. The result of latter free command shows more free memory available than ...
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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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How to display `top` results sorted by memory usage in real time?

How can I display the top results in my terminal in real time so that the list is sorted by memory usage?
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34 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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108 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
756 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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56 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
54 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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Memory problems when compressing and transferring a large number of small files (1TB in total)

I have 5 million files which take up about 1TB of storage space. I need to transfer these files to a third party. What's the best way to do this? I have tried reducing the size using .tar.gz, but ...
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1answer
96 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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624 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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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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2answers
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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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2answers
64 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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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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3answers
271 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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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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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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/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
40 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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64 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
50 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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460 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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81 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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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
568 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
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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
77 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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24 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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58 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
22 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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22 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 ...
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46 views

Limit the inode cache used by a command

I want to run a task with limits on the kernel objects that they will indirectly trigger. Note that this is not about the memory, threads, etc. used by the application, but about memory used by the ...
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1answer
5k views

How to check which process is using most memory

When I check free in one of Prod server it showing 70% of memory is being used: total used free shared buffers cached Mem: 164923172 141171860 23751312 ...
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1answer
33 views

Can swap space accomodate single process?

From what I understand, the swap space can be used to swap out inactive processes to free up memory. But can a single process take advantage of swap space? For example, if my system has little memory, ...
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Is there a way to limit the amount of memory a particular process can use in Unix?

I need to test a process for memory management. I do not have the source, so I need to do all the testing from the OS side. I want to be able to say something like limitmemory 400k -p <pid> ...
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Ubuntu 14.04 using 100% swap space, with more than 40GB free memory, why?

I'm a bit at a loss trying to figure out why this would be the case. Can anyone provide some helpful ideas on troubleshooting this? $ free -m total used free shared ...
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39 views

How to check if allocated memory was freed?

Does anyone know which command I need to enter on the terminal, so I can check whether all allocated memory was successfully freed?
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32 views

Does /proc/[pid]/status always use kB?

Particularly, does proc always list the VmRSS value in kB? I can't find a solid answer on the documentation, although it appears that it sticks to one unit.
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What memory is not used by processes and freed by `echo 3 > /proc/sys/vm/drop_caches`?

Without programs open, my computer uses about 512M of memory. Yesterday, I had nothing open, yet 2 GB of mem use (used - cache = 2153): total used free shared buffers ...