In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.
2
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1answer
16 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 ...
3
votes
3answers
29 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?
1
vote
1answer
36 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
votes
1answer
21 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:
...
7
votes
0answers
56 views
+50
Allocated Memory difference in xen guests after using Linux 3+ kernel
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 ...
2
votes
0answers
19 views
Anonymous mmap zero-filled? [migrated]
In Linux, the mmap(2) man page explains that an anonymous mapping
. . . is not backed by any file; its contents are initialized to zero.
The FreeBSD mmap(2) man page does not make a similar ...
3
votes
0answers
25 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 ...
1
vote
0answers
30 views
How do you track memory usage in a ksh93 script
We have a number of ksh scripts that run forever (inside a while loop), or at least until a shutdown event is delivered to them. We had a project where these scripts where converted to ksh93 (and ...
1
vote
0answers
33 views
Understanding the Buddy Allocator [closed]
I have a conceptual doubt in understanding the way Linux Kernel manages Free blocks. Here is what I interpreted through reading so far.
The Buddy Allocator implementation is allocation scheme that ...
-1
votes
1answer
26 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 ...
1
vote
2answers
44 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 ...
0
votes
0answers
21 views
Shared memory counted as cached
When i start my application that allocates about 5GB of shared memory, i instantly see that the the cache is up by 5GB.
Why is the application shared memory is counted as also as cached memory? ...
5
votes
2answers
97 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 ...
3
votes
1answer
55 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 ...
4
votes
1answer
57 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?
4
votes
1answer
50 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 ...
0
votes
1answer
40 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
36 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 ...
1
vote
1answer
81 views
How to measure on Linux the peak memory of an application after has ended
How do I measure the peak memory of an application running on Linux?
I run this app in batch so I cannot use RSS since, it reports the current memory. I need the peak memory that the application has ...
0
votes
2answers
57 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 ...
2
votes
4answers
96 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 ...
1
vote
2answers
88 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?
1
vote
1answer
96 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 ...
1
vote
1answer
97 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: ...
3
votes
3answers
115 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 ...
6
votes
1answer
254 views
How to blacklist a correct bad RAM sector according to MemTest86+ error imdocation?
MemTest86+ (the version included with Ubuntu 13.04) says
Failing address: 002f796c48 - 759.5 MB
What should I specify in the memmap kernel parameter to bypass this area?
I've tried running ...
10
votes
3answers
394 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 ...
2
votes
1answer
495 views
How to find Heap memory of a running process? [duplicate]
I would Like to know how to find the heap captured of a process which is running in the background?
Is there any command by which you can find the process heap memory and here the process is still ...
0
votes
1answer
35 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%)
...
3
votes
1answer
85 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 ...
1
vote
1answer
53 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 ...
1
vote
3answers
83 views
Linux / JVM - OutOfMemoryError: unable to create new native thread
I have a memory problem with a Linux server (CentOS). It is a VM. Below is the context.
It has 70Gb of RAM. There are 2 tomcat running on it.
One tomcat is given a heap of 13Gb and the other one a ...
1
vote
1answer
99 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
50 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 ...
2
votes
0answers
93 views
Linux: Total swap used = swap used by processes +?
So, I'm trying to do some investigation on where does swap use come from in a system with high swap usage:
# free
total used free shared buffers cached
Mem: ...
1
vote
0answers
60 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 ...
3
votes
0answers
64 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?
...
2
votes
3answers
218 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}')"
...
3
votes
1answer
196 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, ...
0
votes
1answer
217 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 ...
2
votes
2answers
118 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 ...
1
vote
3answers
114 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
vote
1answer
72 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 ...
4
votes
1answer
388 views
How to monitor RAM ECC errors on Ivy Bridge Xeon E3 processor in Linux?
How can I monitor if there are any errors in RAM that get corrected by ECC? The processor is an Intel Xeon (Ivy Bridge) processor, the operating system is Scientific Linux 6.3. On a previous system I ...
0
votes
2answers
734 views
How can i free up memory / manage memory on a linux box?
I am running two Ubuntu 12.04 servers (no GUI / desktop) using canonical's cloud images on Amazon EC2. One is a micro with 613MB of RAM and one is a medium with 3.75GB of RAM.
I only have opscode's ...
1
vote
1answer
34 views
Not using specific memory regions due to errors
I have just installed some new RAM (2x1GB, 667, sticks from 2x512MB, 533, sticks) into an old system (perfectly valid), and all was working fine, until now.
I have been having some issues when the ...
1
vote
2answers
74 views
Where is the frame.h located in modern Linux implementations? (ubuntu specifically)
A book I am reading refers to an include file that shows how a stack frame looks on one's UNIX system.
In particular: /usr/include/sys/frame.h
I am having trouble finding the modern equivalent. ...
0
votes
0answers
142 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 ...
0
votes
1answer
237 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 ...
1
vote
2answers
947 views
Bash script that automatically kills processes when CPU/memory usage gets too high
I have created a script that kills processes if CPU and/or memory usage hits 80%. It creates a list of killed processes when this happens. What can I do to improve it?
while [ 1 ];
do
echo
echo ...
