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

5
votes
0answers
150 views

What is using 4GB of memory? (Not cache, not a process, not slab, not shm)

We have some EC2 servers that experience a memory leak over days or weeks. Eventually there gets to be many GB of memory that is used (according to tools like free and htop) and, if we don't restart ...
5
votes
0answers
157 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 ...
4
votes
0answers
31 views

Why does /proc/*/status not account for all swap used on a system?

I have a system that has been swapping recently and am unable to account for all swap that is shown as in use by tools like 'free' or 'top'. Specifically, I can account for 19GB of 28GB swap used ...
4
votes
0answers
120 views

Why are slab objects not reclaimed automatically

Everyday after a full system backup, various programs are failing with read errors until I run echo 2 > /proc/sys/vm/drop_caches to free reclaimable slab objects. For example, here's the output of ...
4
votes
0answers
311 views

What does hierarchy support do in cgroup?

cgroup has 2 options for memory control: memory.use_hierarchy = 1 : use hierarchy memory.use_hierarchy = 0 : use flat hierarchy, according to this answer What is the difference between the two? I ...
4
votes
0answers
725 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 ...
4
votes
0answers
906 views

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 ...
3
votes
0answers
87 views

Boot rescue kernel at high memory address using kexec on arm

Summary: Crashkernel boots at 512MB address in RAM with kexec -e/-l but not with kexec -p - why? Embedded platform with Marvell Armada XP (MV78460) (ARMv7 with 4 cores) and 1GB of RAM. production ...
3
votes
0answers
61 views

Memory consumption over variable period of time

There are a number of questions on this StackExchange about memory consumption, notably: How to check which process is using most memory How to display top results sorted by memory usage in real ...
3
votes
0answers
196 views

How to read the output of the show-memory-usage SysRq?

I couldn’t find any (recent) documentation on reading the output of the show-memory-usage SysRq (Alt+SysRq+m). So what can one learn from looking at it? Here is an example output form my box (Kernel ...
3
votes
0answers
306 views

Why does saving a KVM-QEMU VM requires additional memory?

I have three VMs running on Red Hat Enterprise Linux with 8 GB RAM, each of the VMs has 3 GB allocated, and I also run a 512 MB VM. If we also consider the guest OS's memory usage (usually 1.5 GB due ...
3
votes
0answers
228 views

Why message queues are not being used for any system level applications in Ubuntu OS?

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 ...
3
votes
0answers
390 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
25 views

Any way to specify process to call on Linux when OOM activates?

On my embedded system I'd like to record when the system OOM killer actives, e.g. by setting an env. variable in u-boot. Is there any way to specify a hook function to call on the OOM event?
2
votes
0answers
107 views

Is unreclaimable memory allocated to slab considered used or available cache?

After evaluating /proc/meminfo, I see the following information: $cat /proc/meminfo MemTotal: 197852592 kB MemFree: 64755992 kB MemAvailable: 65655112 kB Buffers: 4388 kB ...
2
votes
0answers
46 views

What does it mean when a private VM page is none of `rwx`?

UPDATE: It's a padding: every such non-rwx area is preceded with a readable and/or writable area and together they constitute a 64Mb segment (for 64bit architecture). A relevant question on SO: ...
2
votes
0answers
76 views

wProcess killed by OOM killer when plenty of memory apparently free

I'm working on an embedded ARM-based platform. 32-bit, 512MB of RAM, no swap. Linux 3.10.53 (some variety of Ubuntu, if that's relevant). Some code I'm working on is getting consistently oom-killed, ...
2
votes
0answers
180 views

Portable way to parse /proc/meminfo

I'm having trouble finding a generic code that work, here, for both CentOS 5/6 and CentOS 7 versions pc the /proc/meminfo file. I Want to compute the "Real Used memory" like free does. (amounts ...
2
votes
0answers
336 views

is THP good or bad for MySQL Server?

Linux kernel new feature called Transparent Huge Pages (THP) which is by default enabled on CentOS 6.x and above OS. Is THP good for MySQL DB machine? I am trying following to disabled THP but seems ...
2
votes
0answers
204 views

How can the RES memory reported for a Java process be higher than the VIRT memory?

I've been monitoring a Java process (Oracle Weblogic) using TOP and have observed that sometimes the following will happen: RES will increase from it's usual stable level of 2,097,152 KB up to ...
2
votes
0answers
61 views

What uses Linux “application memory”?

Just for fun, I wanted to watch what ls -lR / does to my "buffers" memory on a Linux system. As expected, the value increased. But I noticed that the "application memory" (i.e. "used" - (buffers + ...
2
votes
0answers
104 views

Cgroups - memory subsystem

I want to set the memory.limit_in_bytes parameter for a control group and disable OOM, so processes freeze when the limit is reached. But i want to change that limit dynamically, if there is more ...
2
votes
0answers
121 views

Getting non-stored password from Icedove

I've recently changed my mail password (because of Heartbleed), but I've forgotten the new one. When entering the new password in Icedove, I didn't think of clicking "remember password", but the ...
2
votes
0answers
417 views

Debian 64-bit sees less than 4GB of RAM

I have a Debian wheezy (7.4) amd64 virtual machine running under VirtualBox 4.3.10 on a Win7 x64 host with AMD A10-5700 processor. The virtual machine is configured with 16GB of memory (the host has ...
2
votes
0answers
432 views

What is the structure of Libvirt Qemu VM dump/save files?

I need to do some exploration of Qemu-KVM virtual machines physical memory (particularly I need to check the fact of the physical memory intersection). In order to do that I'm trying to save VM's ...
2
votes
0answers
137 views

Automatically memtest and then boot

Is there some way to reboot server, so it runs memtest (say, 1 or 2 passes) and then reboots back to Linux and writes report to some log? This feature in Windows Server 2012 helped me to diagnose bad ...
2
votes
0answers
130 views

Why does the kernel boot faster with less memory allocated?

This is not a important question, I'm just curious. Something strange happened, which isn't quiet clear to me: In the kernel command line, the amount of the memory can be set statically with the ...
2
votes
0answers
741 views

CentOS memory allocation

I was running my VPS with CentOS on 1G memory, but I saw the memory was getting "full" so I had 1G extra installed. This VPS is one I rent at a hosting company. That company did most of the ...
2
votes
0answers
486 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. ...
2
votes
0answers
823 views

How to decide how much memory to allocate per core for MPI app GENE?

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' ...
2
votes
0answers
950 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 ...
1
vote
0answers
40 views

Memory Leak trackdown

I have a server running Red Hat Enterprise Linux Server release 6.7. The server runs a number of java processes including a tomcat server with nginx webserver. The server has 12 GB of ram allocated ...
1
vote
0answers
45 views

Creating a sparse (automatically expanding and contracting) swap file with hole-punching support

I have this crazy idea, and want to know the pitfalls of such an approach (or whether it can even work with no deadlocks.. etc). The goal is to create an automatically expanding and contracting ...
1
vote
0answers
23 views

getting kernel: pci 0001:02:00.0: BAR 0: can\'t allocate mem resource [0x60100000-0x600fffff] on reboot

On rebooting the board we are getting following errors: err: kernel: pci 0001:02:00.0: BAR 0: can\'t allocate mem resource [0x60100000-0x600fffff] Warning: kernel: aer: probe of 0001:02:00.0:pcie01 ...
1
vote
0answers
18 views

How to check if an application uses my video card memory?

We can check the core, cpu utiliztion, memory etc of a particular process. Can we check if it uses video card too and if it is how much memory it is using?
1
vote
0answers
22 views

Working my way through dmesg output on a custom 3.5.4 kernel

Having read this thread here: What does the Virtual kernel Memory Layout in dmesg imply? It sounds like 'lowmem' is exclusively meant for kernel-space. [ 0.000000] virtual kernel memory layout: ...
1
vote
0answers
776 views

Bash session errors on commands: “fork: Cannot allocate memory”

I have a bash session open to a remote server and something is wrong. I created a directory "test" and touched the files inside touch 1 2 3 4 5. I then tried to copy the directory cp test/ test2/ and ...
1
vote
0answers
47 views

How can I profile/benchmark RAM performance?

I would like to know if my memory hardware is a bottleneck of my system performance. I am dealing with really old hardware (late 2000). If there is room for improvement, I would like to upgrade. ...
1
vote
0answers
63 views

What is kswapd_low_wmark_hit_quickly from /proc/vmstat

What does this parameter mean? # cat /proc/vmstat | grep low kswapd_low_wmark_hit_quickly 2
1
vote
0answers
30 views

Which parts of Memory can Swap Support

For this question, "swap" does not include RAM and only refers to the configured space on the disk. According to, http://www.ualberta.ca/CNS/RESEARCH/LinuxClusters/mem.html, a program's memory usage ...
1
vote
0answers
218 views

Ubuntu 14.04 using 100% swap space, with more than 40GB free memory, why?

I'm a bit at a loss trying to figure out why this would be the case. Can anyone provide some helpful ideas on troubleshooting this? $ free -m total used free shared ...
1
vote
0answers
108 views

Out of Memory with unused memory and swap

I have a strange error on my Raspberry Pi2. System is archlinuxarm. Short after boot (about 30 secs), the system states that it is out of memory, resulting in closing many applications, most time ...
1
vote
0answers
276 views

Java process gets killed frequently by OOM - Killer on upgraded hardware

I am running solr on an Ubuntu server along with 4 other java processes. Current index size is 30 GB. My solr process gets killed frequently in few hours. It clearly mentions that its an OOM killer. I ...
1
vote
0answers
723 views

About mem and vmem

I am working with a cluster machine running under linux. I have a shell script that uses mpirun to submit my jobs to the cluster machine. In that same script, I can choose the number of nodes that ...
1
vote
0answers
91 views

how to limit dma address to specific range in linux kernel?

I want to limit the dma address the device can access to 0x0100_0000~0x03ff_ffff. But I don't know how to set the dma_mask and coherent_dma_mask. It's easy to set the "dma mask" for a range start ...
1
vote
0answers
391 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. ...
1
vote
0answers
312 views

Inexplicable high memory usage (apparently not caused by programs, buffers, cache, or slab cache)

I've got a server that claims 1.7 of its 2 GB of RAM are used, but the combined memory usage of the running processes doesn't come anywhere near that figure: $ free -m total used ...
1
vote
0answers
426 views

How to cause memory fragmentation on a Linux based embedded device?

Hardware ARM What am I trying to do: Answer: I am trying to create memory fragmentation on a Linux 2.6.31 based swapless embedded device. Why: Answer:I am trying to port some patches to Linux ...
1
vote
0answers
1k views

dovecot. Can't allocate memory, but free -m show available memory

I trying to send mail with PHP (engine - Drupal). But it can't send mail and write message about it in to log (nothing more that adressed). Part of /var/log/mail.err : Feb 14 19:55:30 hivede13-3220 ...
1
vote
0answers
30 views

Amount of memory transfer on a running Linux

Can I determinate the amount of RAM exchange (between the CPU and the RAM) on a running Linux system? I'm not looking for the max RAM speed (then memtest would be valid answer). I'm looking for the ...