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

2
votes
1answer
692 views

Can I use pmap to find out Memory utilization?

I want to measure memory utilization of my Apache Server. Can I use the pmap command and pass all the process IDs of httpd and take that as total utilization? pmap PID1 PID2 .... It seems that pmap ...
7
votes
4answers
20k views

Swap usage too high?

I have a Debian Sid box, freshly installed about a month ago, with no desktop apps running at the moment. Any command I try to run (via ssh) makes the hard disk work very hard. The system worked ...
7
votes
2answers
9k views

How to place / store a file in memory on linux?

I have read somewhere that one can put a file on a linux system into memory, and loading it will be superfast. How do I do this? How do I verify the file is loaded from memory?
1
vote
2answers
995 views

raspberry pi keeps killing imagemagicks convert

My raspberry Pi keeps killing imagemagick's convert command when I'm resizing images, especially larger images. Is there any way I can prevent this?
4
votes
0answers
769 views

Are there any tools to test MTD/JFFS2 for Linux 2.4 kernels

I have some issues with a platform I support and I suspect memory problems. I wanted to check the Flash parts using some MTD JFFS2 test tools, I found a link to a bunch on this site. However they ...
2
votes
2answers
370 views

Monitor single process to logfile perodicly

Based on this question, I would like to log the performance of a specific process, with a frequency of say one second, to a csv (comma separated value) log file. Something like: ...
3
votes
1answer
382 views

Use all system memory in Solaris

I am doing server testing and intentionally trying to crash a virtual Solaris server by using all memory. Server has a ulimit of 15 GB (several hundred GB of total system/swap memory). Is there a ...
2
votes
1answer
1k views

Concept of memory mapping in Unix like systems

Can some one explain in an easy to understand way the concept of memory mappings (achieved by mmap() system call) in Unix like systems ? When do we require this functionality ?
0
votes
1answer
479 views

Memory usage caused by MySQL or Apache?

Here is a screenshot of my usage today on an idle unfinished cms drupal site with a maximum of 14 added modules besides core and no activity or users. As you can see I am at my limit which is crazy ...
2
votes
1answer
929 views

Where is max process size specified?

I've got a RHEL4 machine with 1TB of memory and have discovered that malloc and mmap refuse to allocate any memory above 512GB. Meanwhile, I don't seem to have a problem with RHEL5 machines. I'm ...
6
votes
1answer
4k views

Tracking down “missing” memory usage in linux

On an Arch 3.6.7 x86_64 kernel I am trying to account for the memory usage of the system, which the more I look at it, the more there appears to be a hole (in the accounting of used memory, a non-hole ...
2
votes
2answers
1k views

RSS(resident set size) is differ when use pmap and ps command

$ pmap -x 10400 10400: ./a.out Address Kbytes RSS Dirty Mode Mapping 0000000000400000 0 0 0 r-x-- a.out 0000000000600000 0 4 4 r---- a.out ...
0
votes
0answers
38 views

free reporting huge amount of used memory [duplicate]

Possible Duplicate: real memory usage I recently got access to a machine which remains rather unoccupied. I looked up the available memory and was surprised to see that so much memory has ...
1
vote
1answer
2k views

glibc malloc() uses mmap() for small blocks of memory allocation?

I learned that on Linux the glibc’s malloc() uses mmap() for very big chunk of memories and brk() is used for small allocations. However that does not seem to be the case when I experiment the theory ...
8
votes
1answer
4k views

Does free() unmap the memory of a process?

I am running a C program on Linux 2.6.16 kernel. I do not think there are memory leaks in my program however the memory consumption for the program remains stable after certain operations and does not ...
13
votes
2answers
1k views

Why does Linux purge the memory cache when it is nearly full?

Here's what the memory graph looks like on a VPS running CentOS with 512MB of RAM and nginx/php-fpm/mysqld serving (mostly static) content to a couple thousand visitors per day. (those are days on ...
0
votes
1answer
803 views

Swap space not used

I recently installed Debian 6.0.6. Here are the machine's states: CPU - AMD XP 3000+ RAM - 1 Gig HDD - IDE 80 Gig I primarily use this machine for developing toy personal projects. When I run ...
1
vote
4answers
6k views

how to increase memory usage manually?

There is Solaris 10 OS on our server, and I would like to make test on this server. For this test memory usage should be high. So I wonder if there is an easy way to increase memory usage manually ?
2
votes
2answers
2k views

Find the PID of top CPU/MEM usage, save to a shell variable

Is there any way to get the PID of the top CPU/MEM usage, I need to use that in a script, top command doesn't seem to work for it.
0
votes
2answers
302 views

Total RAM used by a program with `ps`? [duplicate]

Possible Duplicate: Measuring RAM usage of a program I am trying to use ps to benchmark a program, I'm just not sure which flags to use. I would like to get the amount of RAM the program ...
9
votes
3answers
476 views

Physically break into box? (Memory & disk)

I have a VPS. I might be able to encrypt my partition but I havent tried. My VPS company I believe can reset my root password although the only SSH key I see is my own. With all my data I have it ...
1
vote
1answer
5k views

How to know maximum memory usage of a process? [duplicate]

Possible Duplicate: Measuring RAM usage of a program I have a process, which is quite short-running (about 10 minutes), but memory heavy. I want to know how much memory does the process ...
2
votes
1answer
1k views

Memory ussage for TCP or named pipe message buffers?

I have a group of programs that I was stress testing today. I drastically shot up the input load to the program and it worked at first, but I had an apparent memory leak sucking up memory. The only ...
5
votes
1answer
186 views

How to create external, filesystem, read-only entrypoint for process internal memory?

Target platform is GNU/Linux. Let's say I have: void *p I want to be create entrypoint for that internal memory in filesystem like: /tmp/my_entry_point And I'd like to be able to read that ...
5
votes
1answer
363 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 ...
1
vote
0answers
227 views

memtester runs faster after couple of runs

I am using this test tool : http://pyropus.ca/software/memtester/ And I noticed that first 3 iterations take 4 hours but 30 iterations take only 12 hours. I was hoping that 30 iterations will take 40 ...
10
votes
2answers
37k views

What do top's %MEM and VSZ mean?

I'm working on an embedded Linux system (128MB RAM) without any swap partition. Below is its top output: Mem: 37824K used, 88564K free, 0K shrd, 0K buff, 23468K cached CPU: 0% usr 0% sys 0% nic ...
6
votes
2answers
3k 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 ...
7
votes
2answers
2k views

An oom killer thats baffling me

I am not able to understand why would kernel issue this oom killer when I see enough memory is available: Also why are there so many kernel cache pages allocated? I say enough memory is available ...
4
votes
2answers
371 views

crontab, instance, memory issues+spamming

I have a cronjob that runs php5 wp-cron.php every minute to update my website. However something happened and i had 30+ instance of it (31 is marked on this one dump of ps aux). It ate up my ram, ...
2
votes
2answers
513 views

Do Solaris 10 and 11 still use slab allocation for their kernel memory allocator

If not, what do they use. Please provide a source.
3
votes
1answer
1k views

High memory (user space) and highmem (kernel space)

Each process has 2 memory area: User space (high memory) and kernel space (low memmory). In the kernel space, are the first 896 MB used for mapping kernel code (not fully 1 GB)? This means, when a ...
0
votes
2answers
1k views

Tomcat does not get enough memory

i'm trying to setup a jira instance on my vServer. I've got min. 1 GB ram and max. 2 GB ram. It was runing on my friends Server with only 512 MB ram. The first error was: ...
0
votes
2answers
314 views

Critical Memory [duplicate]

Possible Duplicate: free: output format My Redhat server shows the following: free -m ============= total used free shared buffers cached Mem: ...
4
votes
1answer
730 views

Rationale for making user space text segment start at 0x8048000

I read somewhere that (at least since Linux v. 2.6) all user-space code is placed at load address 0x8048000 in the virtual memory address space. My own observations confirm this. I have done a cat ...
1
vote
1answer
709 views

How to make the system automatically kill some processes?

Sometimes my computer starts to behave sluggishly after running too many programs/processes simultaneously, at points almost looking crashed/frozen. Using Debian Linux, is there a way to ...
1
vote
2answers
382 views

Sudden burst in free memory

I'm experiencing some strange memory management behaviour on Squeeze with Kernel 2.6. I'm trying to get to the bottom of this with nmon. Sometimes this will freeze up the system for 30 seconds to 5 ...
4
votes
0answers
971 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 ...
2
votes
1answer
750 views

How to get the maximum virtual set size of a unix process during its lifetime?

The time command includes a format parameter "M", which according to the time man page on Linux is used for the following: Maximum resident set size of the process during its lifetime, in Kilobytes. ...
1
vote
4answers
17k views

How to find information about the RAM using the Terminal? [duplicate]

Possible Duplicate: Can I identify my RAM without shutting down linux? I need to know it to check the compatibility... I wanna know the type/size/model, etc. Can someone help? Thanks.
2
votes
2answers
337 views

How to compare usage of memory by Window Managers?

I'd like to test a few window managers to see which of them takes less memory and CPU in certain time period (so is better choice for older computers). I'd like to make the tests myself (not to read a ...
0
votes
1answer
530 views

Smallest GUI VNC setup

I'm setting up VNC on my VPS with 768mb ram. What would be the best setup to save the most memory? Right now I tried Gnome-core with vncserver but it uses a lot of RAM. I remember having a VNC ...
5
votes
1answer
3k views

How can I tell what memory RAM address range is being used by uboot?

I am in uboot and was wondering, how could I tell what RAM address range is being used by uboot. uboot needs memory to run so it might be using some of the RAM. I want to avoid modifying those RAM ...
2
votes
2answers
901 views

RAM usage doesn't add up? (Free+used < total)

Lately I've been noticing that my monitoring script which reads from /proc/meminfo and /proc/<pid> has been showing odd readings, where several hundred MB seem to be missing. htop is showing the ...
1
vote
2answers
4k views

free / top difference. Does free show virtual memory?

free -m shows me the following in my system: total used free shared buffers cached Mem: 3954 3842 111 0 248 2585 -/+ ...
15
votes
1answer
13k views

How can I test the RAM for data corruption on an ARM-based system?

I have an embedded device. It is ARM based, with Linux 2.6.31 and has 256 MB RAM. I wanted to get some ideas/tips on what is the most effective way to test the device RAM for data corruptions. Is ...
8
votes
2answers
2k 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 ...
16
votes
3answers
16k views

How can I reserve a block of memory from the Linux kernel?

I have a device that needs a block of memory that is reserved solely for it, without the OS intervening. Is there any way to tell BIOS or the OS that a block of memory is reserved, and it must not ...
9
votes
1answer
652 views

MySQL gets killed by OS every 25 days or so

About 4 months ago we migrated from MS SQL Server to MySQL 5.5. Since then we have been experiencing an issue once approximately ever 25 days since where CentOS runs out of memory and as a result it ...
2
votes
1answer
462 views

What is parallel memory allocation?

I'm trying to understand what parallel memory allocation is. I think I understand what 'memory allocation' is but I don't understand the term 'parallel'. Something to do with multiple processors ...