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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8
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1answer
13k 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 ...
7
votes
3answers
2k 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 ...
26
votes
7answers
27k views

Correctly determining memory usage in Linux

I'm a bit confused on some of the results I am seeing from "ps" and "free". On my server, this is the result of "free -m" [root@server ~]# free -m total used free shared ...
3
votes
1answer
2k 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 ...
14
votes
2answers
15k 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 ...
2
votes
1answer
996 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 ...
7
votes
2answers
2k views

What is the appropriate value of vm.swappiness when using zram?

I'm using zram on my computer as a compressed RAM-backed swap. When the system needs to swap something out, swapping it to a zram-backed swap file is more or less equivalent to compressing that data ...
1
vote
0answers
271 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?
0
votes
1answer
699 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 ...
3
votes
2answers
474 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 ...
19
votes
1answer
14k 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 ...
15
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2answers
9k views

How to Determine the Amount of RAM Slots In Use?

I forgot how many RAM modules are installed on my laptop. I do not want to unscrew it but want to look it up on the console. How do I gather this information?
2
votes
1answer
517 views

Memory profiling the linux kernel on an embedded device

I have an linux kernel 2.6.30 on an ARM based embedded device and I have to do some kernel memory usage profiling on the device. I am thinking of monitoring the ps output on various kernel threads ...
3
votes
1answer
649 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 ...
4
votes
1answer
3k 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
7
votes
1answer
3k 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
2answers
5k 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 ...
19
votes
3answers
4k views

What does the vm.swappiness parameter really control?

Per the kernel documentation: This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase aggressiveness, lower values decrease the amount of swap. ...
1
vote
1answer
653 views

What is the optimum swap size on Linux for a heavily threaded program?

I using an Amazon EC2 server small instance and by default it allows 382 threads per process. However, I wish to run 10,000 threads in a single process. Recently, I learned that this can be done by ...
2
votes
0answers
323 views

Odd Inode/Ram cache drops happening in CentOS

I run a CentOS 5.7 machine (64bit) with 24GB ram and 4x SAS drives in RAID10 setup. This machine runs nginx/1.0.10, php-fpm & xcache. About a month back the RAM usage of this machine has changed. ...
7
votes
1answer
3k views

getrusage system call: what is “maximum resident set size”

man getrusage 2 says ru_maxrss (since Linux 2.6.32) This is the maximum resident set size used (in kilobytes). For RUSAGE_CHILDREN, this is the resident set size of the largest ...
2
votes
1answer
98 views

application to see the cpu architecture in a figure

I remember there was an application that showed, in the console, or in a simple picture, the memory architecture of the system: what caches were shared by which processors, etc. but I can't remember ...
2
votes
0answers
155 views

Need good ideas about improving any Linux service [closed]

I have a project assigned to me by OS teacher to choose any Linux service and improve it. Currently I am totally blank in this. I am not sure which service should I use which can easily be implemented ...
6
votes
3answers
4k views

What is the formula to determine how much memory a socket consumes under Linux?

I'm doing some capacity planning and I was wondering if there is a formula that I could use to predict (from a memory standpoint) how many TCP connections I could handle on my server. At the moment, ...
6
votes
1answer
4k views

Why does Linux show both more and less memory than I physically have installed?

I know about swap - this question isn't about that. In dmesg, the Linux (x86-64) kernel tells me this about how much memory I have: [ 0.000000] Memory: 3890880k/4915200k available (6073k kernel ...
3
votes
1answer
412 views

Impossible pmap results

Nautilus is taking up 450 MiB according to System Monitor (Ubuntu 10.04). $pmap <PID of Nautilus> ... total 1578276K Is pmap reporting 1.5 GiB of memory here? I'm trying to find out ...
2
votes
3answers
601 views

Is there a way to tell the system to keep a folder to reside in memory?

I'm developing a Java EE web application and I'm trying to speed up the testing process. To do so I was wondering if there is a way to tell the system to keep my build folder in system memory?
8
votes
2answers
6k views

How to limit available virtual memory per process

Occasionally some processes on my GNU/Linux desktop (such as gv and gnash) use up the physical memory and cause thrashing. Since these processes aren't important, I want them to be automatically ...
8
votes
1answer
3k views

System hanging when it runs out of memory

I've got an eeePC 900a: it has a 8GB flash as disk and only 1GB of RAM. The Linux distribution installed on it is ArchLinux. When the system runs out of memory it becomes extremely unresponsive: it ...
2
votes
2answers
288 views

Memory reporting issues

When I view the system monitor it reports that I'm only using 48% of ram. Same with gkrellm. But all of the command line utilities report different. Here is the output to free and /proc/meminfo. ...
2
votes
3answers
6k views

How to get free memory on AIX?

How can I see the free memory on an AIX? There is no free -m under it. AIX oslevel: 6100-03-03-0943
2
votes
2answers
420 views

What tool(s) should I use to test my hardware for errors?

Are there any Linux tools (command line, or Live CD) that will test hardware components for errors (hard drive, RAM, CPU, graphics card, buses) and show me some detailed output with wrong parts etc.?
3
votes
2answers
783 views

Restricting memory area for linux kernel

I am running ltib Linux on P1022RDK (P1022 Core) platform. I have 512 MB = 0x20000000 memory. I want my Linux kernel to use the second half of the board memory (i.e from 256 MB to 512 MB) and want the ...
2
votes
2answers
818 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 .. ...
1
vote
3answers
114 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 ...
8
votes
4answers
2k views

Suspend/resume single process to/from disk

On occasion, we would like to suspend memory-intensive processes on our Ubuntu and OS X servers to temporarily free up some RAM for other jobs. If all we were worried about was CPU usage, a simple ...
3
votes
2answers
4k views

How to find out total memory resource usage with ps?

With ps command I can find out how much memory each program uses: ps -u mertnuhoglu -o pcpu,rss,pid,command Is it possible to find out the sums of each type of resource usage as well, easily?
13
votes
3answers
3k views

Increasing kernel memory size

I have an embedded board with 512MB of RAM running Linux 2.6.29 and UBoot bootloader. But the kernel is able to utilize only 128MB of RAM. I tried changing the value of XCODE_MEMSIZE, which I think ...
5
votes
1answer
537 views

How can I search/browse in some process's memory?

I'm using MacOS X 10.7 and I'm not very familiar with unix. Is there a command for a search in some process's memory for a string?
2
votes
1answer
3k views

Is the file table in the filesystem or in memory?

In the context of operating system control tables, does the term "file tables" refer to a data structure that is part of the filesystem, or that is in main memory (and in which case I assume it would ...
4
votes
1answer
725 views

Behavior of mmap'd memory on memory pressure

I have a large tar file (60GB) containing image files. I'm using mmap() on this entire file to read in these images, which are accessed randomly. I'm using mmap() for the following reasons: Thread ...
3
votes
2answers
274 views

Access memory via a flat file in Linux

I understand everything is a flat file in Linux. How hard is it to dump the contents of the main memory into a flat file? Does it already exist in Linux? If yes, what's the path to the file? What are ...
2
votes
2answers
2k views

gnome-keyring-daemon couldn't allocate secure memory

I run logcheck on my Debian Linux system to get alerted to unusual lines in my log files, and recently I saw the following in /var/log/messages: gnome-keyring-daemon: couldn't allocate secure memory ...
2
votes
1answer
111 views

Is there any method to mount a block of memory as a filesystem in linux?

I have a question,in linux, is there any method to mount a block of memory as a filesystem? For example, in X86 architecture, when power on, I reserve a block of memory about 8 Mbytes, and then when ...
6
votes
2answers
972 views

Difference between free -m and ps -euf

I'm not an expert on linux so I do apologize in advance for the silly question. I have a vps machine with ubuntu 10.04 and 512Mb of RAM. I'm trying to guess how much memory is available after running ...
12
votes
1answer
529 views

Does window minimizing free memory usage?

Both the undisplayed maximized window and minimized window are invisible to the end user. By undisplayed I mean an inactive maximized window covered by the active window. There is a difference ...
23
votes
4answers
7k 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. ...
1
vote
1answer
492 views

Is there a way to kick kswapd and make it swap out pages?

Even though I have set swappiness to 100 and enabled swap, nothing is being swapped out. This is probably because I don't have high memory pressure at the moment. For testing purposes though, I want ...
7
votes
3answers
3k views

Linux Kernel logical address space organisation

According to "Write Great Code" in almost all OS run time memory is organized into following regions: OS | Stack | Heap | Text | Static | Storage/BSS [In increasing address fashion] User ...
1
vote
1answer
2k views

Disable Address space layout randomization (ASLR) for my processes

I want to run some programs in Linux where I want to disable Address Space Layout Randomization (ASLR). I know to disable it at system level, which is by setting /proc/sys/kernel/randomize_va_space to ...