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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Memory mapping of the Linux kernel : 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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3answers
112 views

What is the lowest level I can see my system running?

Let me try and clarify. Is there any way for me to see very very low level activity on my computer? Stuff like: register content opcodes being sent specific memory addresses Or anything lower ...
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4answers
2k 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 ?
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2answers
910 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.
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3answers
381 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 ...
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2answers
187 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 ...
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2answers
499 views

Linux I/O shared memory access

I'm pretty confused on how linux manages I/O shared memory to communicate with devices that use it. If I understood it correctly linux kernel starts mapped at 0x100000 (to avoid the first megabyte ...
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1answer
2k 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 ...
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4answers
3k views

Measuring RAM usage of a program

time is a brilliant command if you want to figure out how much CPU time a given command takes. I am looking for something similar that can measure the max RAM usage of the program and any children. ...
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1answer
521 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 ...
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1answer
142 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 ...
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126 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 ...
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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 ...
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2answers
1k 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 ...
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2answers
636 views

Xvfb does not release memory

We want to create screenshots of websites for our software, and we are doing this by using CutyCapt with Xvfb. Unfortunatly every time CutyCapt takes a screenshot, the memory of Xvfb increases .. ...
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2answers
233 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, ...
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2answers
318 views
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4answers
2k views

Read the stack of another process?

I'm trying to read a child process's stack but with no luck. I know it is possible using ptrace, but ptrace's interface allows you to read only one word at a time, and I'm trying to scan a larger ...
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2answers
635 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: ...
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2answers
155 views

Critical Memory [duplicate]

Possible Duplicate: free: output format My Redhat server shows the following: free -m ============= total used free shared buffers cached Mem: ...
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2answers
215 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 ...
3
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1answer
405 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 ...
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1answer
496 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 ...
2
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1answer
379 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. ...
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1answer
199 views

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 ...
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4answers
6k 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.
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3answers
1k views

How to limit resource usage to save CPU+RAM for a certain process?

I have a dev server on which sshd sometimes stops working because the machine runs out of RAM. Yes we are running low on memory and upgrading is not a feasible choice right now. What I want to do is ...
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1answer
377 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 ...
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1answer
4k 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 ...
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2answers
2k 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 -/+ ...
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1answer
475 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 ...
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1answer
235 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 ...
2
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1answer
126 views

Memory Management: Faulting virtual addresses

I came across the following on http://tldp.org/LDP/tlk/mm/memory.html If the faulting virtual address is invalid this means that the process has attempted to access a virtual address that it ...
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1answer
675 views

confusing about PSS in /proc/pid/maps

I found one great explanation about smaps from info about smaps To my understanding, I thought that shared_clean + shared_dirty + private_clean + private_dirty = rss I wrote a program to ...
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1answer
7k views

Need explanation on Resident Set Size/Virtual Size

I found that pidstat would be a good tool to monitor processes. I want to calculate the average memory usage of a particular process. Here is an example output: 02:34:36 PM PID minflt/s ...
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2answers
682 views

Limiting the Size of Apache HTTPD Memory Footprint

I have a web server running Cent OS 5 with Apache. I have over 1GB of Ram and the MaxSpareServers set to 15. This would be fine under most situations, but for some reason my httpd processes are ...
7
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3answers
1k views

Exploring RAM contents

I am using a redis Database and would like to explore the contents of the RAM the application is using. I feel the explanation of why I want to do this will make more sense then the question I would ...
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2answers
10k views

How to create a user with limited RAM usage?

So I have 4 GB RAM + 4GB swap. I want to create a user with limited ram and swap: 3 GB RAM and 1 GB swap. Is such thing possible? Is it possible to start applications with limited RAM and swap ...
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1answer
1k views

What is the buffers column in the output from free?

These questions briefly list the format of the free command, noting that buffers is kernel memory that must be written out to disk and cache is file data that does not need to be written disk. On my ...
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1answer
655 views

How often is PSS value updated for a given process in /proc/pid/smaps

So if n processes are sharing a library L with size M then the contribution to their PSS is M/n. Now imagine one of the process terminates. So the contribution would be M/(n-1). Q1: My question is ...
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1answer
509 views

Connecting various process attributes reported by top, ps, /proc/pid/statm, /proc/pid/status, /proc/pid/smaps [closed]

Here are some of the common attributes I figured out: top(VIRT) , smem(VSS), /proc/pid/statm (1st entry in pages), /proc/pid/status (VmSize), ps(VSZ) top(RES) , smem(RSS), /proc/pid/statm (2nd entry ...
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0answers
218 views

Process VSS and Size: entry in /proc/pid/smaps

I was wondering why the sum of all 'Size:' entries in /proc/pid/smaps does not equal the process VSS as reported by top, ps, /proc/pid/status VmSize, /proc/pid/statm 1st entry? Any clues?
3
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2answers
337 views

`free`: output format

I use free to get the amount of free space on some of my servers. Its output is something like: $ free -m total used free shared buffers cached Mem: 374 ...
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1answer
2k views

Mathematical connection between SZ RSS and VSZ in ps o/p?

I wanted to know what mathematical connection is there between the SZ, RSZ and VSZ output in ps output e.g. ps -p 2363 -o sz,rss,vsz
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1answer
546 views

tmpfs and vm.swappiness

I have started tuning a bit Linux VM performance on my system (yes. I know that vm.swappiness=0 will kill kittens but I found 30-40 as much better for me as it improved my latency - probably at cost ...
6
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1answer
2k views

How can I observe memory bandwidth?

I have an embedded Linux ARM system that is showing significantly less throughput than expected on both Ethernet and USB. I suspect the memory may be contributing. Is there a way to observe the memory ...
4
votes
1answer
4k views

How to limit application memory usage?

I have spend 2 hours reading questions about this matter, and still there is some misunderstanding. I have this process: USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1452 0.4 1.8 ...
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1answer
2k views

What are shmpages in laymans terms?

What exactly are shmpages in the grand scheme of kernel and memory terminology. If I'm hitting a shmpages limit, what does that mean? I'm also curious if this applies to more than linux
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302 views

VMO Changes After Adding New RAM To AIX?

We have a server at a client site running AIX 5.3, which we just up the RAM to 32GB, from initially 16GB (if I'm not mistaken). This server is our Application server running J2EE applications on top ...
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2answers
3k views

Why does my system show only 3.2 GiB of RAM when I definitely have 4.0 GiB

I have 2x2 GiB sticks of RAM installed. Running memtest86 from the grub boot menu confirms this.. memtest86 reports no errors. However every which way I check my available memory in a running ...