In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.
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 ...
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 ...
23
votes
3answers
12k 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 ...
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
2answers
432 views
Xvfb does not release memory
We want to create screenshots of websites for our software, and we are doing this by using CutyCapt with Xvfb.
Unfortunatly every time CutyCapt takes a screenshot, the memory of Xvfb increases .. ...
4
votes
2answers
164 views
crontab, instance, memory issues+spamming
I have a cronjob that runs php5 wp-cron.php every minute to update my website.
However something happened and i had 30+ instance of it (31 is marked on this one dump of ps aux). It ate up my ram, ...
2
votes
2answers
185 views
Do Solaris 10 and 11 still use slab allocation for their kernel memory allocator
If not, what do they use. Please provide a source.
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 ...
0
votes
2answers
377 views
Tomcat does not get enough memory
i'm trying to setup a jira instance on my vServer.
I've got min. 1 GB ram and max. 2 GB ram.
It was runing on my friends Server with only 512 MB ram.
The first error was:
...
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: ...
1
vote
2answers
148 views
Sudden burst in free memory
I'm experiencing some strange memory management behaviour on Squeeze with Kernel 2.6. I'm trying to get to the bottom of this with nmon.
Sometimes this will freeze up the system for 30 seconds to 5 ...
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
1answer
387 views
How to make the system automatically kill some processes?
Sometimes my computer starts to behave sluggishly after running too many programs/processes simultaneously, at points almost looking crashed/frozen. Using Debian Linux, is there a way to ...
2
votes
1answer
234 views
How to get the maximum virtual set size of a unix process during its lifetime?
The time command includes a format parameter "M", which according to the time man page on Linux is used for the following:
Maximum resident set size of the process during its lifetime, in Kilobytes.
...
2
votes
1answer
152 views
Compare usage of memory by window managers
I'd like to test a few window managers to see which of them takes less memory and CPU in certain time period (so is better choice for older computers). I'd like to make the tests myself (not to read a ...
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.
19
votes
3answers
972 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 ...
0
votes
1answer
312 views
Smallest GUI VNC setup
I'm setting up VNC on my VPS with 768mb ram.
What would be the best setup to save the most memory?
Right now I tried Gnome-core with vncserver but it uses a lot of RAM.
I remember having a VNC ...
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 ...
1
vote
2answers
1k views
free / top difference. Does free show virtual memory?
free -m shows me the following in my system:
total used free shared buffers cached
Mem: 3954 3842 111 0 248 2585
-/+ ...
8
votes
1answer
414 views
MySQL gets killed by OS every 25 days or so
About 4 months ago we migrated from MS SQL Server to MySQL 5.5. Since then we have been experiencing an issue once approximately ever 25 days since where CentOS runs out of memory and as a result it ...
2
votes
1answer
145 views
What is parallel memory allocation?
I'm trying to understand what parallel memory allocation is.
I think I understand what 'memory allocation' is but I don't understand the term 'parallel'.
Something to do with multiple processors ...
2
votes
1answer
96 views
Memory Management: Faulting virtual addresses
I came across the following on http://tldp.org/LDP/tlk/mm/memory.html
If the faulting virtual address is invalid this means that the process
has attempted to access a virtual address that it ...
1
vote
1answer
380 views
confusing about PSS in /proc/pid/maps
I found one great explanation about smaps from info about smaps
To my understanding, I thought that
shared_clean + shared_dirty + private_clean + private_dirty = rss
I wrote a program to ...
4
votes
1answer
3k views
Need explanation on Resident Set Size/Virtual Size
I found that pidstat would be a good tool to monitor processes. I want to calculate the average memory usage of a particular process. Here is an example output:
02:34:36 PM PID minflt/s ...
4
votes
2answers
503 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 ...
4
votes
3answers
292 views
Exploring RAM contents
I am using a redis Database and would like to explore the contents of the RAM the application is using.
I feel the explanation of why I want to do this will make more sense then the question I would ...
9
votes
2answers
4k views
How to create a user with limited RAM usage?
So I have 4 GB RAM + 4GB swap. I want to create a user with limited ram and swap: 3 GB RAM and 1 GB swap. Is such thing possible? Is it possible to start applications with limited RAM and swap ...
2
votes
1answer
353 views
What is the buffers column in the output from free?
These questions briefly list the format of the free command, noting that buffers is kernel memory that must be written out to disk and cache is file data that does not need to be written disk.
On my ...
2
votes
1answer
254 views
How often is PSS value updated for a given process in /proc/pid/smaps
So if n processes are sharing a library L with size M then the contribution to their PSS is M/n.
Now imagine one of the process terminates. So the contribution would be M/(n-1).
Q1: My question is ...
0
votes
1answer
317 views
Connecting various process attributes reported by top, ps, /proc/pid/statm, /proc/pid/status, /proc/pid/smaps [closed]
Here are some of the common attributes I figured out:
top(VIRT) , smem(VSS), /proc/pid/statm (1st entry in pages), /proc/pid/status (VmSize), ps(VSZ)
top(RES) , smem(RSS), /proc/pid/statm (2nd entry ...
1
vote
0answers
172 views
Process VSS and Size: entry in /proc/pid/smaps
I was wondering why the sum of all 'Size:' entries in /proc/pid/smaps does not equal the process VSS as reported by top, ps, /proc/pid/status VmSize, /proc/pid/statm 1st entry?
Any clues?
2
votes
2answers
212 views
`free`: output format
I use free to get the amount of free space on some of my servers. Its output is something like:
$ free -m
total used free shared buffers cached
Mem: 374 ...
2
votes
1answer
1k views
Mathematical connection between SZ RSS and VSZ in ps o/p?
I wanted to know what mathematical connection is there between the SZ, RSZ and VSZ output in ps output e.g.
ps -p 2363 -o sz,rss,vsz
2
votes
1answer
392 views
tmpfs and vm.swappiness
I have started tuning a bit Linux VM performance on my system (yes. I know that vm.swappiness=0 will kill kittens but I found 30-40 as much better for me as it improved my latency - probably at cost ...
6
votes
1answer
1k views
How can I observe memory bandwidth?
I have an embedded Linux ARM system that is showing significantly less throughput than expected on both Ethernet and USB. I suspect the memory may be contributing. Is there a way to observe the memory ...
7
votes
1answer
910 views
What does the vm.swappiness parameter really contol?
Per the kernel documentation:
This control is used to define how aggressive the kernel will swap
memory pages. Higher values will increase agressiveness, lower values
decrease the amount of swap.
...
4
votes
1answer
3k views
How to limit application memory usage?
I have spend 2 hours reading questions about this matter, and still there is some misunderstanding.
I have this process:
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1452 0.4 1.8 ...
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
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 ...
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
484 views
What is the optimum swap size on Linux for a heavily threaded program?
I using an Amazon EC2 server small instance and by default it allows 382 threads per process. However, I wish to run 10,000 threads in a single process. Recently, I learned that this can be done by ...
2
votes
0answers
188 views
Odd Inode/Ram cache drops happening in CentOS
I run a CentOS 5.7 machine (64bit) with 24GB ram and 4x SAS drives in RAID10 setup.
This machine runs nginx/1.0.10, php-fpm & xcache. About a month back the RAM usage of this machine has changed.
...
3
votes
1answer
859 views
getrusage system call: what is “maximum resident set size”
man getrusage 2 says
ru_maxrss (since Linux 2.6.32)
This is the maximum resident set size used (in kilobytes). For RUSAGE_CHILDREN, this is the resident set size of the largest
...
2
votes
0answers
89 views
Need good ideas about improving any Linux service [closed]
I have a project assigned to me by OS teacher to choose any Linux service and improve it. Currently I am totally blank in this. I am not sure which service should I use which can easily be implemented ...
6
votes
3answers
1k views
What is the formula to determine how much memory a socket consumes under Linux?
I'm doing some capacity planning and I was wondering if there is a formula that I could use to predict (from a memory standpoint) how many TCP connections I could handle on my server. At the moment, ...
3
votes
1answer
243 views
Impossible pmap results
Nautilus is taking up 450 MiB according to System Monitor (Ubuntu 10.04).
$pmap <PID of Nautilus>
...
total 1578276K
Is pmap reporting 1.5 GiB of memory here? I'm trying to find out ...
2
votes
3answers
210 views
Is there a way to tell the system to keep a folder to reside in memory?
I'm developing a Java EE web application and I'm trying to speed up the testing process. To do so I was wondering if there is a way to tell the system to keep my build folder in system memory?
7
votes
2answers
2k views
How to limit available virtual memory per process
Occasionally some processes on my GNU/Linux desktop (such as gv and gnash) use up the physical memory and cause thrashing. Since these processes aren't important, I want them to be automatically ...
