In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.

learn more… | top users | synonyms

1
vote
1answer
140 views

32 bit OS memory limitation on NUMA systems

Running 32 bit Rhel 6.5 with kernel 2.6.32-431.el6.i686 on a server with 46 Gb RAM and NUMA support. CONFIG_X86_PAE=y Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz OS is not able to see more than 14GB ...
0
votes
1answer
217 views

buffer cache and free memory

Below is the output of free in Ubuntu: $ free total used free shared buffers cached Mem: 8173180 8013092 160088 0 1076276 3091136 -/+ ...
1
vote
0answers
470 views

About Linux Memory Compaction (CONFIG_COMPACTION)

I have a question regarding memory compaction on Linux. Generally compaction is triggered when system cannot satisfy a large contiguous memory allocation. This causes the compaction to run on all ...
3
votes
2answers
1k views

/proc/pid/maps addresses (and converting them)

When looking at the memory maps in /proc/pid/maps, we can see different length addresses 00400000-0042e000 r-xp 00000000 fb:01 268953 /bin/nano 0062e000-0062f000 r--p ...
3
votes
1answer
1k views

kernel: disabling /dev/kmem and /dev/mem

I understand that /dev/kmem and /dev/mem provide access to the memory (i.e. raw RAM) of the system. I am also aware, that /dev/kmem can be completely disabled in kernel and that access can be ...
2
votes
0answers
78 views

Getting non-stored password from Icedove

I've recently changed my mail password (because of Heartbleed), but I've forgotten the new one. When entering the new password in Icedove, I didn't think of clicking "remember password", but the ...
0
votes
1answer
57 views

Is memory in user space always low to high

I mean that if its true always that first lower addresses are used and then increment the address to access higher address. Can it be in reverse order?
5
votes
1answer
93 views

How the network packets are transferred to the memory on linux?

Is there some command or tool for monitoring network packets and how those packets are handled by the memory and than proceeded to the CPU on linux platform? Using tcpdump I can capture many apache ...
2
votes
0answers
368 views

Debian 64-bit sees less than 4GB of RAM

I have a Debian wheezy (7.4) amd64 virtual machine running under VirtualBox 4.3.10 on a Win7 x64 host with AMD A10-5700 processor. The virtual machine is configured with 16GB of memory (the host has ...
0
votes
1answer
55 views

Configure the OOM to avoid having the system grind to a halt

I have an SSD and therefore no swap. However, when I open a lot of tabs in the browser, the system tends to grind to a halt. If I'm lucky, I can close one or two tabs before the system is completely ...
5
votes
1answer
206 views

can initramfs be paged out to swap disk?

I am using initramfs to boot Centos via PXE. The initramfs used memory is listed within the "cached" value in /proc/meminfo or via free. Since I need to calculate performance data, I need to know ...
3
votes
1answer
2k views

Why is swap used when a lot of memory is still free? [duplicate]

In the below 2.6.18 Linux Kernel (Red Hat) server, there is a lot of free memory, but I see some swap is used. I always thought of swap as an overflow when memory has been depleted. Why would it ...
0
votes
1answer
175 views

Can continually assigning a variable in a shell script cause a memory leak?

I've written a short script to copy Apache's server status to a log: #Save date and time to a variable dt=$(date) #Echo date and time to the log file as it's not included in server-status echo "Time ...
0
votes
1answer
139 views

Having an independent console to kill rogue process?

Sometimes a flash plugin starts using all the mem and CPU or an app is also behaving "naughtily" and my system starts to crawl until i finally get a terminal with htop up and kill the rogue process, ...
2
votes
0answers
246 views

What is the structure of Libvirt Qemu VM dump/save files?

I need to do some exploration of Qemu-KVM virtual machines physical memory (particularly I need to check the fact of the physical memory intersection). In order to do that I'm trying to save VM's ...
15
votes
1answer
4k views

Loading of shared libraries and RAM usage

I'm wondering about the way Linux manages shared libraries. (actually I'm talking about Maemo Fremantle, a Debian-based distro released in 2009 running on 256MB RAM). Let's assume we have two ...
0
votes
1answer
97 views

What happens to the files when they are being decrypted?

I have the server's webroot directory mounted on a partition which is being protected with LUKS encryption. I want to know what happens to the files within when that partition is being decrypted. Does ...
5
votes
1answer
319 views

Virtual kernel memory layout: negative values [closed]

i'm porting drivers for omap3-board to 3.5 kernel. When I start board I see it: Memory: 256MB = 256MB total Memory: 253564k/253564k available, 8580k reserved, 3226106074K highmem Virtual kernel ...
2
votes
0answers
98 views

Automatically memtest and then boot

Is there some way to reboot server, so it runs memtest (say, 1 or 2 passes) and then reboots back to Linux and writes report to some log? This feature in Windows Server 2012 helped me to diagnose bad ...
8
votes
7answers
3k views

cron Vs. sleep - which is the better one in terms of efficient cpu/memory utilization?

The Case: I need to run some commands/script at certain intervals of time and for this I have two options - 1. set up a cron-job or, 2. implement a loop with sleep in the script itself. Question: ...
1
vote
0answers
29 views

About the usage of Memory in a linux server [duplicate]

I find my server's memory usage is so high, part of the output of command free is shown below: total used free shared buffers cached Mem: 82446460 81961412 ...
3
votes
1answer
47 views

program executing for 2 days

I have a java program which implements the Hungarian algorithm. I made changes to the existing code in such a way that the input is read from file. I have a pretty huge input around 32,000 rows for ...
1
vote
0answers
27 views

Set memory allocation for applications in Ubuntu [duplicate]

I have an application running under Ubuntu that tries to consume all available memory. Is there a way to specify and restrict the allocations available for a given application?
1
vote
0answers
243 views

How to cause memory fragmentation on a Linux based embedded device?

Hardware ARM What am I trying to do: Answer: I am trying to create memory fragmentation on a Linux 2.6.31 based swapless embedded device. Why: Answer:I am trying to port some patches to Linux ...
2
votes
0answers
93 views

Why does the kernel boot faster with less memory allocated?

This is not a important question, I'm just curious. Something strange happened, which isn't quiet clear to me: In the kernel command line, the amount of the memory can be set statically with the ...
4
votes
3answers
164 views

What happens in UNIX/Linux when a program is bigger then size of memory?

I was wondering how embedded systems are able run programs bigger than the size of memory. If I had 1 GB of memory and the program was 1.5 GB, would the program load? Are there systems that only use ...
2
votes
2answers
1k views

Are limits in linux (like those controlled by ulimit or /etc/security/limits.conf) per user or per user per process?

I saw three copies of a process running and one of them cored in what seems like memory issue. Each individually occupies about 3-4 GB of memory..would a limit account for killing one of them? And if ...
17
votes
1answer
6k views

What is maximum RAM supportable by Linux?

What is the maximum supportable RAM by Linux? Assume that hardware is/supports 64-bit. Among all Linux distros. Does it go up to 16 exabytes, or is it limited like with Windows which I believe is 192 ...
3
votes
1answer
1k 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 ...
0
votes
1answer
215 views

mdadm large memory consumption [closed]

I am building a RAID 6 with mdadm (8 WD Red 3 Tb) on Ubuntu 13.10x64 server with ext4 filesystem. When I download torrent on the array, server RAM is filled for maximum cap (8 Gb) memory is free when ...
1
vote
0answers
902 views

dovecot. Can't allocate memory, but free -m show available memory

I trying to send mail with PHP (engine - Drupal). But it can't send mail and write message about it in to log (nothing more that adressed). Part of /var/log/mail.err : Feb 14 19:55:30 hivede13-3220 ...
3
votes
3answers
1k views

Why does MemTotal in /proc/meminfo change?

I monitor value from /proc/meminfo file, namely the MemTotal: number. It changes if a ram module breaks, roughly by size of the memory module - this is obvious. I know the definition for the field ...
9
votes
2answers
1k views

Turning off swapping for only one process with cgroups?

I would like to turn off swapping for only one process. Swap should work as usual for the other processes. How I can implement this with cgroups?
1
vote
1answer
99 views

Limiting processes by memory under Linux

We must launch several hungry processes on a Linux system. These processes often need several Go (~5Go) of memory to run (total memory: 16Go RAM + 2Go swap). At first, when the system was running ...
3
votes
1answer
4k 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 ...
0
votes
1answer
1k 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 ...
5
votes
1answer
2k views

Does kernel: EDAC MC0: UE page 0x0 point to bad memory, a driver, or something else?

kernel: EDAC MC0: UE page 0x0, offset 0x0, grain 0, row 7, labels ":": i3200 UE All of a sudden today, our CentOS release 6.4 (Final) system started throwing EDAC errors. I rebooted, and the errors ...
1
vote
1answer
3k views

What's exactly Compile time, Load time, and Execution time? [closed]

It's said, Compile time -- When it is known at compile time where the process will reside, compile time binding is used to generate the absolute code. Here I'm not sure what is the absolute code? ...
0
votes
1answer
179 views

Preventing a new instance of a program to open when calling it

My problem is with FBI (frame buffer image viewer) for Linux, but my question and any answers are perhaps applicable to more than only that program. I don't know. Anyway… While things are loading on ...
1
vote
0answers
23 views

Amount of memory transfer on a running Linux

Can I determinate the amount of RAM exchange (between the CPU and the RAM) on a running Linux system? I'm not looking for the max RAM speed (then memtest would be valid answer). I'm looking for the ...
88
votes
11answers
42k views

How to fill 90% of the free memory?

I want to do some low-resources testing and for that I need to have 90% of the free memory full. How can I do this on a *nix system?
4
votes
2answers
1k views

Is it possible to trigger OOM-killer on forced swapping?

Is it possible to have the system preemptively swap out inactive pages (vm.swappiness), but invoke the oom-killer when the system runs out of RAM (as opposed to running out of memory) and is forced to ...
21
votes
1answer
18k views

Getting information about a process' memory usage from /proc/pid/smaps

For a given process in /proc/<pid>/smaps, for a given mapping entry what are: Shared_Clean Shared_Dirty Private_Clean Private_Dirty Is Shared_Clean + Shared_Dirty the amount of memory that ...
1
vote
1answer
55 views

Is this method safe or recommended for moving a /home directory?

I have my linux install on a small disk. I want to put the home directory on a different hard-drive. I was thinking of using this and then this. Would this work? Is there a better way? Should I just ...
0
votes
1answer
235 views

Is there something wrong with df output? [duplicate]

I'm using the command df -h to check disk usage on CentOS 6.4. I see an inconsistency with the output. look at the line Filesystem: total 490Gb, used 55Gb, and Available 411Gb. What is it mean? I ...
1
vote
2answers
15k views

Memory usage on SunOS and Linux

I have some doubts with memory usage. Currently I have nagios check who measures used memory from free -m command on Linux. I added another script for memory usage from ...
4
votes
1answer
455 views

Why do the data and code segments completely overlap in Linux?

Context: I'm reading "Understanding the Linux kernel, 3d ed", which uses the 2.6.11 kernel. Question: As I understand, the physical address is obtained by translating the linear address, which is ...
1
vote
0answers
46 views

memory consumption alert

My VPS has reported a memory consumption alert says reached 273% and I cannot access any of my sites. But I checked on the terminal today and it does not look like a memory problem. Am I correct in ...
-2
votes
1answer
93 views

Loading a kernel driver to a specific memory address

How can I load a kernel driver at a specific memory address? How could it be done with the following methods? commands/scripts like insmod or modprobe using C code (not sure if there may exist ...
5
votes
3answers
730 views

Is it possible to support multiple processes without support for Virtual memory?

Is it possible to support multiple processes without support for virtual memory? I would like to know more about it if so.