In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure.

learn more… | top users | synonyms

1
vote
0answers
45 views

Possible slab memory leak related to bio and btrfs?

I'm currently running a rebuild on a btrfs NAS (~20TB) that had a drive failure. It's going to take a few days. My problem is about once every 24 hours the RAM filled up and the kernel starts killing ...
1
vote
1answer
36 views

What does a “Synchronous” type detail mean in dmidecode?

I'm curious if my 2 DIMMs are running dual-channel or not and use: dmidecode -t 17 ... Type Detail: Synchronous ... What does a "Synchronous" type detail mean? Dual-channel?
1
vote
2answers
56 views

How to determine which files are necessary in /bin, /lib, /var, etc.?

I'm currently trying to get an image working for a network boot using somebody else's file contents. The previous images I made keeping all original files present were way too big, so I need to shrink ...
1
vote
1answer
52 views

Limit CPU and Memory usage for C, Java programs at system level

I am building an online code editor for C and Java. Chances are users will write infinite loops. Is there any way I can limit the cpu and memory utilization of these processes at system level settings ...
1
vote
2answers
42 views

U-Boot shell - show memory usage (like Linux free command)

Is there any way of displaying memory usage from U-Boot? I mean operation memory - like sdram - not mmc.. Ideally from shell but I can be happy also with C command as I compile U-Boot myself.
1
vote
1answer
38 views

How to obtain counters for swap-in/swap-out on Linux?

I'm trying to obtain counters for swap-in/swap-out activity on CentOS 6. The intention is to feed raw data into RRDtool to generate graphs, and use it to generate alerts. I've had a look at common ...
1
vote
4answers
2k 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 -/+ ...
11
votes
8answers
6k views

cron Vs. sleep - which is the better one in terms of efficient cpu/memory utilization?

The Case: I need to run some commands/script at certain intervals of time and for this I have two options: set up a cron-job implement a loop with sleep in the script itself. Question: Which is ...
1
vote
0answers
483 views

Debian - Apache 2.2 & mod_php - memory usage

I have a memory problem with my servers (Debian 6.0) where is installed Apache httpd 2.2, mod_php and APC. Actually it seems that httpd allocate all available memory (4GB) when is waiting too much ...
4
votes
2answers
1k 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 ...
5
votes
1answer
11k views

httpd memory usage

Having some problems with httpd (Apache/2.2.29) memory usage. Over time, memory usage in the httpd processes creep up until it's eventually at 100%. Last time I restarted httpd was about 24 hours ...
113
votes
12answers
64k views

How to fill 90% of the free memory?

I want to do some low-resources testing and for that I need to have 90% of the free memory full. How can I do this on a *nix system?
9
votes
2answers
2k views

How to limit the total resources (memory) of a process and its children

There are plenty of questions and answers about constraining the resources of a single process, e.g. RLIMIT_AS can be used to constrain the maximum memory allocated by a process that can be seen as ...
1
vote
1answer
128 views

What page replacement algorithms are used in Linux kernel for OS file cache?

Linux uses the unused portions of memory for file caching, and it cleans up the space when needed. My question is about how it picks a victim page for replacement? There are various algorithms (LRU, ...
1
vote
2answers
122 views

Top command output explanation (in embedded system)

Can someone please help me understand the output that I get from the top command? This is the point that the oom-killer is invoked and kills my main application. What exactly is under the VSZ and %VSZ?...
11
votes
3answers
911 views

When a process forks is its virtual or resident memory copied?

The standard way of making new processes in Linux is that the memory footprint of the parent process is copied and that becomes the environment of the child process until execv is called. What memory ...
3
votes
1answer
23 views

Can I deny use of swap space to a specific process (and have it just get killed)?

While developing some software, a program under test sometimes eats all the memory, then proceeds to yomp into the swap space and start thrashing the disk, leading to a predictable drop in ...
0
votes
4answers
83 views

Get total memory size on sun os through kstat

I have sun os there Following commands are not available prtconf prtdiag psrinfo The only command which is working is kstat. Can any one please help me on finding the total memory size using only ...
4
votes
2answers
2k views

swapoff fails when overcommit_memory==2

I've disabled memory overcommitting by setting overcommit_memory=2. Now when I tried to swapoff, I get this error: swapoff: /dev/sda5: swapoff failed: Cannot allocate memory But I in fact have 0 ...
1
vote
1answer
29 views

How to run a process and find how much memory it uses? [duplicate]

I regularly use time to find out how long a process takes. Is there an equivalent command for memory? The usual ways to find out how much memory a process takes (ps,/proc/meminfo, etc.) work fine for ...
38
votes
5answers
16k 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. ...
1
vote
1answer
76 views

Memory not used any more but still allocated

I have something kind of weird going on with memory. I have Ubuntu 14.04 servers with Zimbra 8.6 with kernel (for this one) 3.13.0-37-generic. But I have already seen the problem with other kernels. ...
54
votes
6answers
140k views

How to find which processes are taking all the memory?

I'm looking for somthing like top is to CPU usage. Is there a command line argument for top that does this? Currently, my memory is so full that even 'man top' fails with out of memory :)
6
votes
1answer
315 views

Limit the inode cache used by a command

I want to run a task with limits on the kernel objects that they will indirectly trigger. Note that this is not about the memory, threads, etc. used by the application, but about memory used by the ...
1
vote
1answer
254 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
4answers
7k 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 ...
3
votes
1answer
781 views

Swap appears to not be in use

(I am currently using Ubuntu 14.04 LTS, GNOME environment) tl;dr How can I force more memory swapping (swappiness already at 100)? I have recently been experiencing a lot of system freezes/crashes. ...
3
votes
1answer
74 views

Keep a process in RAM (prevent it from swapping)

I want to keep a process in RAM. It should never go into swap. Is this possible? The process is a Java program. I'm running CentoS 7.
8
votes
3answers
8k views

How to reduce ClamAV memory usage?

I'm running a Ubuntu based web server (Apache, MySQL) on a 512MB VPS. This is more than sufficient for the website it is running (small forum). As I wanted to add some protection against viruses I ...
0
votes
0answers
12 views

How to mmap file w/ HUGE_PAGES to specific memory location (via “memmap=4G$4G”)

Presently working: Device driver to mmap to specific memory location (isolated by boot parameter "memmap=4G$4G") via the remap_pfn_range call. Desired solution: Same/similar outcome using 2M pages ...
1
vote
3answers
140 views

Gentoo Hardened eats 3 GB of memory after running for ~12 hours with very few processes running

I'm running Gentoo Hardened AMD64 using kernel 4.3.3-hardened-r4. With my system only running some basic daemons like wpa_supplicant, cron or DHCP, and with an X session with only Windowmaker, GKrellM ...
0
votes
0answers
20 views

How does disabling data journalling speed up the file system?

How exactly does disabling journalling give a better performance in case of Linux (ext4)?
3
votes
0answers
196 views

Limit system processes using cgroups

My server runs several dozens of processes that are not in my control (mostly monitoring software). According to my application logs, sometimes some of the third party processes try to allocate too ...
0
votes
2answers
87 views

Disk busy 101% all the time

I have an OpenNMS Linux server which is having poor disk performance. The machine is a EC2 inside a VPC. atop shows: iotop shows: How do I reduce the IO numbers and bring down the disk ...
1
vote
1answer
30 views

How to know what exactly is being written or which process is keeping my storage disk busy?

I have a server , which has gone rogue(not really), i ran nmon and saw that its Disk utilization is BAD, its 100% busy writing!! Here is the output : Can someone tell me what is keeping my disk ...
142
votes
7answers
171k views

How to display `top` results sorted by memory usage in real time?

How can I display the top results in my terminal in real time so that the list is sorted by memory usage?
1
vote
0answers
50 views

How can I mount remove /dev/mem to local

This question is relate to this, but more general. Currently I mount remote root by sshfs sshfs -o sshfs_sync,sync_readdir,reconnect,follow_symlinks,direct_io,sync_read root@pi:/ pi /proc is ok, ...
3
votes
3answers
77 views

When interrupting a process, does a memory leak occur?

Lets say I created a program in c/c++, where I manually allocated some variables. Then while running the program, I send an interrupt signal (Ctrl-C). Are those variables freed from memory, or will ...
3
votes
1answer
131 views

free command output: gentoo (redhat?) vs debian

I noticed there is a difference between outputs of free command: On debian: $ free -h total used free shared buffers cached Mem: 4.0G 3.4G ...
7
votes
1answer
35k views

How to check which process is using most memory

When I check free in one of Prod server it showing 70% of memory is being used: total used free shared buffers cached Mem: 164923172 141171860 23751312 ...
2
votes
0answers
38 views

OOM Killer: Processes have a score of over a 1000

All top links when Googling for OOM score seem to indicate that the values must be between -1000 and 1000. I tried to verify that with a simple cat /proc/*/oom_score | sort -n | less and I ...
0
votes
0answers
30 views

Why does .text region of shared libraries is not flagged as VM_SHARED?

When I'm using shmem/mmap to share memory between processes I can see with pmap that it creates virtual memory area that marked as shared. Example: Address Kbytes RSS Dirty Mode ...
8
votes
3answers
5k views

How does stack allocation work in Linux?

Does the OS reserve the fixed amount of valid virtual space for stack or something else? Am I able to produce a stack overflow just by using big local variables? I've wrote a small C program to test ...
0
votes
0answers
40 views

How to calculate the amont of kernel memory allocation on Linux?

My system has 128GB physical memory. However, free -h said I have 125 G total memory. [root@rhel7 ~]# free -h total used free shared buff/cache available Mem: ...
5
votes
1answer
669 views

Finding the source of CoW page faults on OS X

I'm trying to find the source of CoW page faults in some C code on OS X. I would like to use the vminfo DTrace provider, but vminfo isn't available on OS X. On Linux, I can use SystemTap to print a ...
7
votes
2answers
2k views

Memory usage command with syntax similar to the time command

What command shows the memory usage of a program, i am looking for a command that is simple to use and has similar syntax to the time command. I am trying to find the memory usage of a md5 hashing ...
0
votes
1answer
85 views

How do you change the Hugepagesize?

How can I change the pagesize for Hugepages on Linux? I'd like to increase it to 4096 kB or 8192 kB. I'm working specifically with Centos and Amazon Linux. $ grep Hugepagesize /proc/meminfo ...
8
votes
2answers
9k 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?
0
votes
1answer
52 views

-/+ buffers/cache & Swap

When should the usage of swap get started? or How do I know that my swap is being used? At least some times if not always, considering the default swappiness of 60 Also, why does free offer to omit ...
1
vote
1answer
44 views

vmstat -s command fields meaning, specially “pages paged in” vs “pages swapped in”

Most of the fields are understandable but can someone please explain me the difference between "pages paged in" and "pages swapped in"?. I'm pretty sure that swapping is when the entire process is ...