In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.
6
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2answers
510 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 ...
10
votes
1answer
322 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 ...
16
votes
4answers
2k 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. ...
0
votes
1answer
328 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 ...
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 ...
1
vote
1answer
1k 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 ...
10
votes
2answers
2k views
Why does my system show only 3.2 GiB of RAM when I definitely have 4.0 GiB
I have 2x2 GiB sticks of RAM installed.
Running memtest86 from the grub boot menu confirms this.. memtest86 reports no errors.
However every which way I check my available memory in a running ...
1
vote
1answer
191 views
What are the Implications of moving to Huge mem kernel on RHEL4
I've been asked to investigate adding extra memory (> 16gb) to a RHEL 4 server and moving to a huge mem kernel. The server is used for Oracle RAC.
Is it just a case of installing the hugh mem kernel ...
4
votes
2answers
1k views
How to check for hardware errors with software methods?
How can I check for bad blocks, bad memory, etc. using only software solutions? I'm using Ubuntu 11.04.
4
votes
2answers
505 views
Limiting the Size of Apache HTTPD Memory Footprint
I have a web server running Cent OS 5 with Apache. I have over 1GB of Ram and the MaxSpareServers set to 15. This would be fine under most situations, but for some reason my httpd processes are ...
19
votes
3answers
976 views
How to limit resource usage to save CPU+RAM for a certain process?
I have a dev server on which sshd sometimes stops working because the machine runs out of RAM. Yes we are running low on memory and upgrading is not a feasible choice right now. What I want to do is ...
8
votes
2answers
1k views
real memory usage
if I understand correctly, in the following output produced by free, 3535m is the actual free memory available to applications, only 413m is used, is this correct? need some clarification on the ...
1
vote
1answer
332 views
Fedora 15 - Limited RAM Access
I have an issue with Fedora 15's available memory. The laptop it is installed on has 4GB of SDRAM, but Fedora only sees 2GB.
[njozwiak@calvin xpmc6720]$ free -m
total used ...
1
vote
0answers
382 views
How to find memory per core on multicore CPU?
This is required information for some MPI using app that I am working with...
From its Makefile template:
#insert memory per core and uncomment the following line
#PREPROC= -D'MB_PER_CORE=750'
...
5
votes
4answers
613 views
Does optimizing for size reduce runtime memory usage as well as binary size?
Does optimizing for size with gcc -Os only reduce the binary size of a program, or does it reduce its runtime memory usage as well? I know what exactly the results are depend on the specific code, but ...
3
votes
1answer
435 views
Solution to get data from memory of a process
If I'm using Firefox and filling out a big form (with lots of text to write), and for some reason I accidentally press F5 and all my text in the forms is lost, I can use e.g. HxD on Windows to ...
3
votes
0answers
235 views
VMO Changes After Adding New RAM To AIX?
We have a server at a client site running AIX 5.3, which we just up the RAM to 32GB, from initially 16GB (if I'm not mistaken).
This server is our Application server running J2EE applications on top ...
2
votes
0answers
404 views
Linux kernel slab usage growing on embedded system
I'm in the process of QA/debugging a project on a custom embedded linux system. The problem we're VERY tight on memory, and even a couple megs can cause issues with our software.
What I'm seeing ...
4
votes
5answers
312 views
Unpredictable memory explosions
The main server at my company has recently been having a lot of downtime. For reasons that neither I nor the other admins can determine, it has random (VERY sudden) explosions in memory. It becomes ...
2
votes
1answer
586 views
CentOS 5.6 x86 64 Not seeing all my memory
So I installed CentOS 5.6 on a box at my house and it is not recognizing all my memory. I have 2gb in the machine but when you run a 'free -m' or a 'top' or a 'cat /proc/meminfo' it only shows that ...
4
votes
1answer
441 views
Tracking huge buffer usage under Linux
I have a Linux server running under Debian Lenny with 4Go of RAM.
It doesn't run much, just:
Postfix/spamassassin (daemon mode)
Bind9
KVM (one guest - 1Go of RAM for it)
Every day at exactly 3:05 ...
3
votes
2answers
2k views
What is the difference between 32-bit PAE and 64-bit kernels?
I ask this only in regards to memory addressing.
I know that a PAE kernel allows the OS to access more memory than a standard 32-bit kernel, however, what are the other implications? What specific ...
4
votes
1answer
753 views
Disable random memory address generation in my programs
I'm reading "The art of exploitation" and would like to try some experiments, including reading from and writing to various memory address. I've created some simple programs and trying to overwrite ...
3
votes
1answer
215 views
Linux system calls
I want to obtain information about memory used by different users and different processes which users are running and statistics about those processes like memory consumption ,execution speed etc ...
4
votes
1answer
689 views
Linux - why is kernel.shmall so low by default?
I run DB2 on Linux where I have to allocate the vast majority of memory on the machine to shared memory segments.
This page is typical of the info that I've found about shmall/shmmax:
...
5
votes
1answer
277 views
Problem on Linux NAND Root Filesystem
I'm have a JFFS2 root filesystem running on a large NAND device. Every once in a while, when I restart the computer, I get error messages about invalid ELF headers when /sbin/init or /bin/login try ...
1
vote
1answer
93 views
How can I test the system footprint of applications?
I am about to develop a piece of software and I want to ascertain the impact it has on my system. The main things I am look for are load times, memory and CPU usage and shutdown time, although I would ...
8
votes
3answers
2k views
How to detect memory type under Linux?
Which Linux utility can tell me if I have registered or unbuffered ECC memory in my server? Lshw and dmidecode do not work for me; dmidecode provides no information about registered vs. unbuffered:
...
7
votes
3answers
374 views
Memory size for kernel mmap operation
I'm interested in the way Linux mmaps files into the main memory (in my context its for executing, but I guess the mmap process is the same for writing and reading as well) and which size it uses.
So ...
0
votes
4answers
291 views
Mnemonics for Unix functions?
Does anyone have any useful mnemonics for remembering the order of function parameters or the return values of Unix system calls? I am suffering from "memory leaks".
7
votes
2answers
562 views
Memory management principle used by Linux
Is memory management in the Linux Kernel done using paging or segmentation or both?
1
vote
1answer
954 views
How to view and change kernel memory size?
How can i view the kernel's share of memory on a machine? How can I increase it? What should I consider before doing it?
7
votes
2answers
402 views
What governs the limits of shell brace expansion?
In this example I refer to the expansion of a sequence of integers, but perhaps(?) the limits would be relevant to all aspects of brace expansion.. This more general view is also of interest to me.
...
6
votes
2answers
1k views
.dtors looks writable, but attempts to write segfault
This is Ubuntu 9.04, 2.6.28-11-server, 32bit x86
$ cat test.c
main() { int *dt = (int *)0x08049f18; *dt = 1; }
$ readelf -S ./test
...
[18] .dtors PROGBITS 08049f14 000f14 000008 ...
12
votes
4answers
2k views
Read the stack of another process?
I'm trying to read a child process's stack but with no luck.
I know it is possible using ptrace, but ptrace's interface allows you to read only one word at a time, and I'm trying to scan a larger ...
23
votes
3answers
13k views
Limit memory usage for a single Linux process
I'm running pdftoppm to convert a user-provided PDF into a 300DPI image. This works great, except if the user provides an PDF with a very large page size. pdftoppm will allocate enough memory to ...
3
votes
3answers
469 views
Preloading the OOM Killer
I don't have any swap partition/file on my machine, and only 2GB of RAM.
Sometimes it happens that the memory gets saturated by some process (Xorg+browser+compiler+...) and the system hangs ...
4
votes
2answers
851 views
Can I identify my RAM without shutting down linux?
I'd like to price some new RAM for our in-house VMware testing server. (It's a consumer box we use for testing our software on and running business VMs). I've forgotten what kind of RAM it has and I'd ...
3
votes
2answers
598 views
Questions on Linux kernel internals
I was reading "Linux device drivers, 3rd edition" and faced a few kernel items I don't quite understand. Hope gurus on this forum will help me out.
Does the Linux kernel internally operate with ...
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 ...
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 ...
7
votes
6answers
1k views
Is there a tool that allows logging of memory usage?
I want to monitor memory usage of a process, and I want this data to be logged. Does such a tool exist?
7
votes
2answers
711 views
How to find out how much memory a program taking
I use htop to watch my processes, but most of services ran are multi threaded, so they are shown on several lines with a % of memory use which in some cases is the same for all, sometimes it varies ...
4
votes
1answer
1k views
What are shmpages in laymans terms?
What exactly are shmpages in the grand scheme of kernel and memory terminology. If I'm hitting a shmpages limit, what does that mean?
I'm also curious if this applies to more than linux
2
votes
2answers
850 views
Is it possible to execute code in heap space?
I would like to know if i can execute a code piece sitting inside the heap space?
2
votes
1answer
191 views
How to reuse Physical memory in the absence of swapping?
How can I reuse physical memory in the absence of swapping?
5
votes
3answers
411 views
Is it possible to support multiple processes without support for Virtual memory?
Is it possible to support multiple processes without support for virtual memory? I would like to know more about it if so.
5
votes
2answers
694 views
ZONE_NORMAL and it's association with Kernel/User-pages?
Above is presented a case where I have only 512 MB of physical memory. What I have read up so far, is that ZONE_NORMAL is mapped to the kernel virtual address space as shown. Essentially I have a ...
8
votes
2answers
600 views
Kernel Panic because of RAM stick?
one of my RAM sticks causes a Kernel Panic on my Ubuntu 10.10 (something like "not syncing" with a lot of memory adresses shown on screen). It's definitely this one RAM stick and not its socket ...
9
votes
1answer
2k views
What does the Virtual kernel Memory Layout in dmesg imply?
While going through the "Output of dmesg" I could see a list of values which i am not able to understand properly.
Memory: 2047804k/2086248k available (3179k kernel code, 37232k reserved, 1935k ...
