In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.
6
votes
1answer
116 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 ...
1
vote
0answers
13 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
27 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
votes
1answer
21 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%)
...
5
votes
2answers
881 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
98 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 ...
4
votes
1answer
181 views
Virtual kernel memory layout: negative values
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
3answers
55 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 ...
3
votes
1answer
216 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 ...
7
votes
2answers
1k 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?
1
vote
1answer
93 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.
0
votes
1answer
78 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
151 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 ...
1
vote
2answers
201 views
Discrepancy between reported used memory and sum of application memory usage
I'm running a desktop system that quite regularly suffers from lack of memory, this prompted me to investigate what causes the issue in the first place.
Problem is, there's no single process that ...
10
votes
3answers
316 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 ...
4
votes
2answers
273 views
What is “kernel dynamic memory” as reported by smem?
While diagnosing low memory problems in my desktop machine (details at U&L) I've noticed that my noncache "kernel dynamic memory" is big:
# smem -twk
Area Used ...
2
votes
2answers
260 views
Measuring CPU and Memory per user to distribute “cost” of a server
How should I implement approximately correct per-user monitoring on a server? I want a way to split the cost of a server between the users based on their usage. On newer machines (RHEL6) I would use ...
16
votes
6answers
5k 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
votes
2answers
557 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 ...
1
vote
1answer
292 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 ...
3
votes
1answer
169 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
votes
1answer
101 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
votes
1answer
123 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 ...
8
votes
4answers
3k views
how to “unswap” my desktop
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 ...
3
votes
1answer
51 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
32 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
132 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 ...
1
vote
1answer
68 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
42 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
64 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
39 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
votes
2answers
185 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
46 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
156 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 $2}')"
...
3
votes
1answer
105 views
Which parts of an ELF executable get loaded into memory, and where?
What I already know:
An ELF executable has a number of sections, obviously the .text and .data sections get loaded into memory as these are the main parts of the program. But for a program to work, ...
2
votes
2answers
99 views
Where is the virtual memory stored on hard drive?
If a process wants to access a memory address that is not in physical memory, the OS outsources a page frame from physical memory to the hard drive for later use. Where on the hard drive is this data ...
4
votes
1answer
218 views
How to monitor RAM ECC errors on Ivy Bridge Xeon E3 processor in Linux?
How can I monitor if there are any errors in RAM that get corrected by ECC? The processor is an Intel Xeon (Ivy Bridge) processor, the operating system is Scientific Linux 6.3. On a previous system I ...
1
vote
3answers
72 views
Get separate used memory info from free -m comand
As a output of free -m command I got following.
total used free shared buffers cached
Mem: 2496 2260 236 0 5 438
-/+ ...
38
votes
3answers
16k views
How do I read from /proc/$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 ...
1
vote
1answer
55 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 ...
5
votes
3answers
371 views
Why is the theoretical RAM limit for RHEL 6 128 TB and how is this determined?
I'm studying for RHCSA and am confused by a statement I came across in some training material:
There is no practical maximum RAM, as theoretically, you could run 128 TB of RAM on RHEL 6. But ...
5
votes
1answer
2k 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 ...
1
vote
2answers
66 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. ...
2
votes
1answer
84 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 ...
0
votes
2answers
230 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 ...
0
votes
3answers
406 views
kswapd0 takes 99% to 100% CPU in RHEL 6.3
I have 5 systems on which I have just installed RHEL6.
System configuration is
CPU-i7
HDD-500 GB
RAM-2 GB
Swap- 4 GB
I have installed the same software's and all the configuration as per old ...
1
vote
1answer
31 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 ...
5
votes
3answers
1k 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 ...
0
votes
0answers
85 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
674 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 ...
