3
votes
3answers
91 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 ...
5
votes
1answer
86 views
+50
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
294 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 ...
1
vote
1answer
31 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
52 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
64 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 ...
2
votes
0answers
63 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: ...
2
votes
3answers
154 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
104 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
98 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
213 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
208 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
0answers
82 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
74 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
115 views
find total ram memory and swap memory
I need to write a script to find total memory and total swap of several linux server (2000+).
I have one trusted server from where I can login to all these 2000 servers without a password.
When I run ...
0
votes
0answers
80 views
Why message queues were not being used for any application?
In my Linux machine, when i run 'ipcs' command, I have the below information listed
srinivas@srinivas-G41MT-S2:~$ ipcs -a
------ Shared Memory Segments --------
key shmid owner ...
1
vote
1answer
92 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.
3
votes
1answer
102 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 ...
2
votes
2answers
129 views
Does Linux have ways to cache IO with memory
My server has a large amount of memory. However, the amount of IO (each of which is small) is very high.
Is there a way to make a virtual drive out of portion of the memory?
I realize I can also use ...
4
votes
2answers
267 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 ...
1
vote
2answers
198 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 ...
4
votes
1answer
140 views
Limit disk buffer usage in SLES 11SP2 to allow more efficient memory overcommit on esxi host
When running VMs on an ESXi host, you can overcommit the memory.
Example: host == 20GB physical RAM
The amount of RAM allocated to each VM is
VM1 == 10gb
VM2 == 10gb
VM3 == 10gb
VM4 == 10gb
The ...
2
votes
2answers
377 views
What a 64 bit Linux can do that 32 bit linux can't?
I ordered a server from fdcserver. Then I realized that, unless changed, fdcserver actually provides 32 bit operating as default.
I logged in using SSH, typed uname -m, and to my horror I saw that I ...
4
votes
2answers
112 views
Why buffers equals to used memory?
I'm using Ubuntu 11.10, virtualized by OpenVZ. That output of free -m shows that buffers is always equal to used.
total used free shared buffers cached
Mem: ...
1
vote
1answer
288 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 ...
4
votes
3answers
961 views
Swap usage too high?
I have a debian sid box, freshly installed about a month ago, with no desktop apps running at the moment.
Any command I try to run (via ssh) makes the hard disk work very hard. The system worked ...
4
votes
2answers
232 views
How to place / store a file in memory on linux?
I have read somewhere that one can put a file on a linux system into memory, and loading it will be superfast.
How do I do this? How do I verify the file is loaded from memory?
2
votes
0answers
129 views
Are there any tools to test MTD/JFFS2 for Linux 2.4 kernels
I have some issues with a platform I support and I suspect memory problems. I wanted to check the Flash parts using some MTD JFFS2 test tools, I found a link to a bunch on this site.
However they ...
2
votes
1answer
166 views
Where is max process size specified?
I've got a RHEL4 machine with 1TB of memory and have discovered that malloc and mmap refuse to allocate any memory above 512GB. Meanwhile, I don't seem to have a problem with RHEL5 machines. I'm ...
6
votes
1answer
287 views
Tracking down “missing” memory usage in linux
On an Arch 3.6.7 x86_64 kernel I am trying to account for the memory usage of the system, which the more I look at it, the more there appears to be a hole (in the accounting of used memory, a non-hole ...
1
vote
2answers
175 views
RSS(resident set size) is differ when use pmap and ps command
$ pmap -x 10400
10400: ./a.out
Address Kbytes RSS Dirty Mode Mapping
0000000000400000 0 0 0 r-x-- a.out
0000000000600000 0 4 4 r---- a.out
...
0
votes
0answers
28 views
free reporting huge amount of used memory [duplicate]
Possible Duplicate:
real memory usage
I recently got access to a machine which remains rather unoccupied. I looked up the available memory and was surprised to see that so much memory has ...
0
votes
1answer
359 views
glibc malloc() uses mmap() for small blocks of memory allocation?
I learned that on Linux the glibc’s malloc() uses mmap() for very big chunk of memories and brk() is used for small allocations. However that does not seem to be the case when I experiment the theory ...
3
votes
1answer
269 views
Does free() unmap the memory of a process?
I am running a C program on Linux 2.6.16 kernel. I do not think there are memory leaks in my program however the memory consumption for the program remains stable after certain operations and does not ...
0
votes
0answers
21 views
All Memory not showing up [duplicate]
Possible Duplicate:
64-bit Linux doesn’t recognize my RAM between 3 and 32 GB
I have installed Oracle Linux 6 on my alien-ware desktop. I have 9GB of DDR3 Ram on the board and the board ...
13
votes
2answers
555 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 ...
2
votes
1answer
242 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 ...
3
votes
1answer
115 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 ...
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
0answers
82 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 ...
6
votes
2answers
4k views
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 ...
5
votes
1answer
369 views
Defragging RAM / OOM failure
This question is fairly lengthy, so I'll ask the questions at the top and then go through my method of coming to the questions:
Did (Busybox based) rm not execute because there wasn't enough ...
6
votes
2answers
640 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 ...
2
votes
1answer
316 views
High memory (user space) and highmem (kernel space)
Each process has 2 memory area: User space (high memory) and kernel space (low memmory). In the kernel space, are the first 896 MB used for mapping kernel code (not fully 1 GB)? This means, when a ...
0
votes
2answers
103 views
Critical Memory [duplicate]
Possible Duplicate:
free: output format
My Redhat server shows the following:
free -m
=============
total used free shared buffers cached
Mem: ...
3
votes
1answer
251 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 ...
1
vote
0answers
279 views
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 ...
1
vote
4answers
2k 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.
3
votes
1answer
214 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 ...
10
votes
1answer
2k 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 ...
