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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Static files give ever changing checksum value on Linux

When I cksum large files (150MB) they will often report different checksums on each call. $ cksum test3 1233504235 170213376 test3 $ cksum test3 825031809 170213376 test3 $ cksum test3 189847968 ...
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1answer
817 views

Which processes swaps memory

I can see swap's total, used, free etc. sizes from top command. But I can't figure out which process uses swap, is it possible to find out swap memory by process? I'm running CentOS 6.3.
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4answers
5k views

How to re-load all running applications from swap space into RAM?

If my desktop run out of memory and swaps a lot then I free or kill the application wasting my RAM. But, after that, all my desktop/applications have been swapped and are horribly slow, do you know a ...
0
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1answer
545 views

very high buffer memory usage [closed]

Is this normal - I've never seen buffers so high? $ cat /proc/meminfo MemTotal: 16332808 kB MemFree: 1112264 kB Buffers: 10630124 kB Cached: 699400 kB SwapCached: 0 kB Active: 3262924 kB Inactive: ...
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2answers
1k views

How can I dump the full system memory?

After starting VirtualBox, the computer became sluggish and then hung completely due to OOM. Usually, OOM should be starting killing processes in order to free up some space, but this did not happen ...
2
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2answers
302 views

a handy tool to measure memory consumption of a program [duplicate]

I develop a C code on Debian. I am looking for a program to monitor memory consumption of my code in real-time. The only value I care is the maximum RAM consumption, it should hold the value even if ...
3
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1answer
278 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 ...
3
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1answer
2k views

/proc/meminfo MemTotal =?

What elements of /proc/meminfo sum up to MemTotal? Example of tee /tmp/proc/meminfo < /proc/meminfo MemTotal: 1279296 kB MemFree: 164092 kB Buffers: 62392 kB Cached: ...
0
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2answers
272 views

what is an application pool?

I'm reading this article: http://www.modrails.com/documentation/Architectural%20overview.html#web_app_models It talks about how Phusion Passenger extends Apache2 to act as an application server. ...
2
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4answers
6k views

What is “System Memory ” displayed in nmon in AIX?

I have a host with AIX 6.1 (6100-04-02-1007) upgraded from AIX 5.1 with Veritas Storage Foundation 5.1. Since the upgrade from AIX 5.3 to 6.1, Run vx services means a lots of memory consumed that I ...
0
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1answer
98 views

What is meant by “a process has open handles to system objects”? [closed]

The following are qualities of a process: virtual address space executable code open handles to system objects a security context a unique process identifier environment variables a priority class ...
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1answer
138 views

Eclipse makes laptop unusable

Currently I can't use my eclipse project. I'm using ArchLinux: -` .o+` rkmax@satellite `ooo/ OS: Arch Linux ...
3
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3answers
75 views

Contents of stack area of a process

I've been going through some Unix text books and I can't have a clear picture on the contents of the stack area of the process. Can anyone please explain or point out some references?
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0answers
282 views

Allocated Memory difference in xen guests after using Linux 3+ kernel [closed]

Can someone explain to me why there is a memory difference in Guests with the same configuration? Hypervisor: xen 4.2 64 bit VM1: Centos 5.7 with 2.6.18-274.el5xen Assigned memory from xen is ...
1
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1answer
478 views

private memory calculated by pmap, a combination of virtual memory size and resident memory size?

You can use the ps command to get the virtual memory size and the resident memory size of a process: $ ps aux | grep apache2 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME ...
2
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1answer
252 views

pmap and memory usage

On Ubuntu 12.04, I have several apache2 processes running (the 1130 parent and the children it spawned), and as you can see, they have around 300-400 mb of virtual memory and 10 mb of resident memory: ...
3
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0answers
134 views

What does hierarchy support do in cgroup?

cgroup has 2 options for memory control: memory.use_hierarchy = 1 : use hierarchy memory.use_hierarchy = 0 : use flat hierarchy, according to this answer What is the difference between the two? I ...
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3answers
551 views

After researching, still confused about monitoring RAM usage

I went through this article, which explains various methods for checking your RAM usage. However, I can't reconcile the different methods and don't know which one is correct. When I first login, I'm ...
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1answer
40 views

get Various types of address used [closed]

How to get various address ranges of a running machine or a crash dump? User virtual address Physical address Bus address Kernel logical address Kernel virtual address I don't need the bus ...
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2answers
1k views

Change the size of my memory pages?

I would like to change my kernel's page size from 4KB to 4MB as I have had a large addition of RAM to my computer and I am never running out of anymore. The idea is that programs requiring large ...
1
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1answer
556 views

Measurement of free ram through /proc/meminfo with ramdisk (initrd)

I am booting a disk image via PXE, it is a full system on an initrd ramdisk. I would like to measure the actual free memory of the system (not including buffers and file system caching). I was told ...
61
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3answers
34k views

How do I read from /proc/$pid/mem under Linux?

The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me $ cat /proc/$$/mem ...
5
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2answers
321 views

What happened to my RAM?

I am trying to understand the basics of the Linux OS. I'm running 64-bit Ubuntu 12.04 on a 64-bit CPU. The system has 2GB of RAM. cat /proc/meminfo MemTotal: 2012040 kB Question 1: Where is ...
4
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1answer
1k views

operation in /dev/shm causes overflow

I am repeating tens of thousands of similar operations in /dev/shm, each with a directory created, files written, and then removed. My assumption used to be that I was actually creating directories ...
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2answers
1k views

What is “automatic stack expansion”?

getrlimit(2) has the following definition in the man pages: RLIMIT_AS The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2) and ...
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1answer
978 views

Invoking memory compaction on linux 2.6.35 kernels and beyond

This LWN article about memory compaction indicates that memory compaction can be invoked in the linux kernel by Writing a node number to /proc/sys/vm/compact_node, causing compaction to happen on ...
3
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1answer
166 views

How to measure the clock pulse of my computer manually?

My PC has two processors, and I know that each one runs at 1.86 GHz. I have just read about clock cycles and I only have a (very) rough understanding, so I apologize beforehand if my question is so ...
0
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2answers
98 views

are daemon tmpfs executables copied unencrypted to memory upon execution? (prevent if so?)

When a daemon is executed, is the executable copied to memory? If so, can it be copied encrypted? If not, is there a way to prevent the executable from being copied to memory? The executable is ...
0
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1answer
103 views

Execute in Place an encrypted ram drive

I have found a few old posts claiming that tmpfs can execute in place. Is this true? If so, how? If not, is there a ram drive alternative? Can this be done with a ram drive that is encrypted? If ...
2
votes
1answer
41 views

Prevent or detect reading of daemon in memory

Is it possible to prevent the memory being used by a daemon to be read by anything else? If not, is it possible to detect an attempt to read? If so, is it possible to get in front of the actual read ...
2
votes
4answers
150 views

How to make sure, that certain functionality (like Alt+Ctrl+F1 switching into tty) is available in havily swapping system?

At the moment, when I accidentally launch application that eats a lot of memory (that causes system to heavily swap), the system become so unresponsive (waiting hours just to see the mouse move/or ...
2
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2answers
201 views

process memory usage

What is usually meant by the phrase process memory usage, what does this actually mean, i.e. what does this memory consist of? And what column does it correspond in ps aux output, RSS or VSZ?
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1answer
3k views

Redhat find process memory usage [duplicate]

When I cat /proc/meminfo I see: MemTotal: 1048576 kB MemFree: 11136 kB Buffers: 0 kB Cached: 0 kB SwapCached: 0 kB Active: 0 kB Inactive: ...
0
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1answer
141 views

“Acpi-State” in slabtop's output gets increased — what is it? Is it a bug?

Since boot it gets increased occupying even more RAM than anything else: Active / Total Objects (% used) : 680608 / 719176 (94.6%) Active / Total Slabs (% used) : 17390 / 17390 (100.0%) ...
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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 ...
3
votes
3answers
218 views

Where is the environment string actual stored?

But when we first time we adding a new name,we have to call malloc to obtain >room for a new list of pointers. We copy the old environment list to this new area and store a pointer to the ...
25
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6answers
24k 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 ...
13
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2answers
818 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 ...
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1answer
153 views

Looking for /procfs documentation, describing values and units of measurement

Surprisingly, comprehensive documentation for /procfs is hard to find. For my specific question, I am looking at: cat /proc/1/statm (let's use pid=1 because it seems to be always there). I just ran ...
0
votes
1answer
267 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
459 views

is free command displaying all physical memory or there is some RAM reserved and hidden?

I am supposed to have 512MB of ram on my VM, however I see 495mb of total ram when I do free command. I would like to know if in case my system really had "precisely" 512MB of physical ram, if in ...
1
vote
1answer
281 views

What's using all of the memory in my VM? It's not the disk cache

I have an issue where when I try to build a really large project, my machine starts swapping (several GB) even though there's plenty of memory (14 GB in fact). When I run free, it shows that it's not ...
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0answers
256 views

“/sbin/yast: fork: Cannot allocate memory” on openSUSE 10.1

I guess I'll come across as a total newbie for asking this, but I get the above message right after starting an ssh session. The reason I opened the ssh session was that I came across a 500 internal ...
0
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2answers
665 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?
3
votes
0answers
118 views

RES memory more than initial and maximum memory for java

We have a java application running on Centos 6.4 what we notice is that the RES is around 370m which is more then the allocated max that is 256m. Does this signify that we the application is leaking? ...
3
votes
3answers
2k views

Human readable system memory reading crom CLI?

On OS X, I get a nice human readable system memory reading like so: printf -v system_memory \ "$(system_profiler SPHardwareDataType \ | awk -F ': ' '/^ +Memory: /{print $2}')" ...
4
votes
1answer
1k views

Which parts of an ELF executable get loaded into memory, and where?

What I already know: An ELF executable has a number of sections, obviously the .text and .data sections get loaded into memory as these are the main parts of the program. But for a program to work, ...
3
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2answers
495 views

Where is the virtual memory stored on hard drive?

If a process wants to access a memory address that is not in physical memory, the OS outsources a page frame from physical memory to the hard drive for later use. Where on the hard drive is this data ...
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3answers
598 views

Get separate used memory info from free -m comand

As a output of free -m command I got following. total used free shared buffers cached Mem: 2496 2260 236 0 5 438 -/+ ...
1
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1answer
185 views

What information exactly is in the access control bits of a page table?

I'm currently learning for an exam in operating systems. This includes learning some basics about page tables, which lead me to the question Why using hierarchical page tables? which mentions that ...