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38
votes
2answers
45k views

How do you empty the buffers and cache on a Linux system?

Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?
-1
votes
0answers
7 views

Asus server stops unexpectedly [on hold]

My Asus server stops suddenly without any notification. I try to find the problem. I use to ultimate boot cd to find what is wrong. I think that it would be in the hardware. I run pated magic. But ...
2
votes
0answers
30 views

Is possible for a manufacturer to fake the RAM limit in the DMI table? [migrated]

I was thinking about upgrading my laptop's RAM. It currently has a 4096 MB module and a 2048 MB module, which I thought I could replace by an 8 GB module: [root@...] # dmidecode -t 17 # dmidecode ...
2
votes
1answer
26 views

Why is my computer sluggish after downloading a lot?

When I download a lot of data (e.g. 3GB) in one go, using a program such as Transmission or Wget, progressively during the downloading, and after it has has finished, the computer always seems ...
0
votes
1answer
48 views

What is the difference between MAC OS X “Virtual Memory” and Linux/Unix Swap? [duplicate]

I would like to understand the difference of MAC OS X "Virtual Memory" and Linux/Unix Swap. I ask this because I observed that MAC OS X "Virtual Memory" seems to work way more efficient (in desktop ...
4
votes
2answers
770 views

How to benchmark RAM memory with a Linux Distro?

I' ve just bought new RAM and I'd like to benchmark and compare with my old. How can I do that?
1
vote
0answers
89 views

Unable to figure out what hogs my RAM [SOLVED] [closed]

Solution: It was file buffers causing the used RAM that didn't show up in htop. To resolve this issue I used the command sync && echo 3 | sudo tee /proc/sys/vm/drop_caches OP: I have a VM ...
1
vote
1answer
45 views

When the RAM is used up, what will happen?

When I ran ImageMagick's convert to convert and combine image files into a pdf file, it will create 10GB temporary dirs and files in /tmp. I am not sure if it did that all the time, or because my ...
1
vote
0answers
13 views

How to interpret numerous processes with exact same RAM usage [duplicate]

I have a VM that processes files, parses the information and saves it to a database. I've been monitoring the resource usage and noticed /usr/sbin/console-kit-daemon --no-daemon.. Below you see a ...
1
vote
3answers
135 views

Is there any way to know the size of L1, L2, L3 cache and RAM in ubuntu?

Is there any way to know the size of L1, L2, L3 caches and RAM in Ubuntu?
1
vote
1answer
91 views

CentOS 6.5 : machine with more that 1 TB RAM => “no free pages available” on boot

I have a upgraded a server with more than 1 TB of RAM, and it is unable to boot. With 768GB of RAM all is working fine. I got the following message : Trying to allocate 1005 pages for VMLINUZ. ...
1
vote
2answers
431 views

Using only 3.3GB but I have 8GB RAM even on Ubuntu 14.04 64bit

I have 2x 4GB(8GB) RAM installed on my motherboard and BIOS/UEFI can confirm it, but on Ubuntu 14.04 64bit only has 3424776kB or 3.266120911GB. uname -a returns: 3.13.0-36-generic #63-Ubuntu SMP Wed ...
10
votes
2answers
2k views

Is using a read only root file system a good idea for embedded setup?

I have been tasked with running Linux as an operating system on an embedded device. The target has an x86 processor and has 8 GB CompactFlash device for storage. I have managed to use buildroot to ...
5
votes
1answer
103 views

Where has my RAM gone & how to interpret atop's memory output?

For a while, I encounter RAM-shortages on my Debian webserver (VPS/virtual machine). This would not be unusual, if they happend on a regular basis. But they do not. Here's a chart from Munin: ...
1
vote
1answer
79 views

file access time after loading file into the cache

I read from here that I could load file into RAM for faster accessing using the below command. cat filename > /dev/null However, I wanted to test if the above statement is really true. So, I ...
0
votes
0answers
28 views

How fast is a process reading/writting virtual memory?

So, we have top, htop, iotop, iostat, vmstat, etc, to measure many different things on Linux, but how can one measure how much MB/s a process is reading and writting to/from RAM, i.e., virtual memory? ...
0
votes
1answer
398 views

swappiness and RAM usage

Been going through this topic - http://askubuntu.com/questions/157793/why-is-swap-being-used-even-though-i-have-plenty-of-free-ram. Turned down swappiness to 10 and then to 0 but my installation is ...
3
votes
4answers
15k views

Java “Could not reserve enough space for object heap” even though there is enough RAM

I am currently having some issues running Java. It won't start because of heap issues. But I have more than 9 GB Ram free (or even 16 GB if you assumed the cache would be empty). This is the error I ...
2
votes
1answer
63 views

Memory Usage in Linux [duplicate]

How to setup limit for process to memory usage? Similar to open files limit in /etc/security/limits.conf: ubuntu soft nofile 4096 ubuntu hard nofile 8192 ...
0
votes
1answer
41 views

What dev folder allows you tell the OS to cache something?

Someone told me that there is a sub folder off of dev that basically allows you to tell the OS to keep the contents of that folder cached in RAM. So if I put some files & directories in ...
0
votes
1answer
84 views

Arch linux weird ram issues

I installed Arch linux (I have reinstalled it a couple of times, actually, in the past 3 months, just to get to know it better). My problem is, that I have 4GB RAM, and as soon as my free RAM hits ...
1
vote
2answers
115 views

Why does Linux only see 3832MB of my 4096MB of RAM?

I am setting up a lot of 64-bit RedHat VMs (VMware vSphere) for our development department in my company. Most of them start with 4096MB of RAM, but Linux only seems to recognize 3832MB. Can anyone ...
7
votes
3answers
4k views

Why is the theoretical RAM limit for RHEL 6 128 TB and how is this determined?

I'm studying for RHCSA and am confused by a statement I came across in some training material: There is no practical maximum RAM, as theoretically, you could run 128 TB of RAM on RHEL 6. But ...
0
votes
0answers
16 views

how to find where buffers/cache are and how to clean them up? [duplicate]

I want to create 20gb ram disk for ANSYS to work in yet on free -g I see: And personally I have not created any ram drives yet. So I wonder how to maximize avaliable ram: how to locate what is using ...
0
votes
1answer
29 views

Virtualbox delete vm ram

If I delete a VM in VirtualBox, what happens with the RAM I used to create that VM? Is it freed?
0
votes
1answer
725 views

How to reduce chrome's virtual memory usage?

I am running a Debian Jessie and having memory issues when using Google Chrome I tried disabling extensions, disabling cache, flushing the cache, and disabling the web 3d rendering, but nothing ...
3
votes
0answers
259 views

My SMDK2416 (for s3c2416) kernel works on 64MRAM but crashed on 128M

I'm currently working on embedded arm linux with smdk2416(s3c2416) The kernel is working on the 64MRAM. Recently, I need to increase the RAM from 64M to 128MB with 64MB on bank0 and 64MB on bank1. ...
3
votes
2answers
1k views

How to tell whether RAM ECC is working?

I'm planning on getting some ECC RAM to replace the non-ECC RAM I currently have installed on my Asus M5A97 Pro motherboard (AMD 970 chipset, FX-6100 CPU). After I install the RAM, how do I tell ...
0
votes
1answer
123 views

should I reduce /dev/shm size?

I have a server wity 8 GB RAM Mem: Total 8031464 Used 5146344 Free 2885120 If I execute # df it always returns this tmpfs 4015732 0 4015732 0% /dev/shm What does it ...
1
vote
0answers
93 views

Swap on video ram in a VM

I have a very small VM running in a cloud with only 512 MB ram. I read, it is possible to use the video card as swap as descriped here: Graphics cards contain a lot of very fast RAM, typically ...
1
vote
1answer
61 views

Compress memory on low Ram VM

Is there a way to get out more out of your limited Ram on a VM? I have a VM running on a cloud hoster and try to optimize a quite low on RAM mashine. I heard, there is a way to compress parts in the ...
4
votes
1answer
309 views

Does tmpfs automatically resize when the amount RAM changes, and does it compete when there's multiple tmpfs?

If I have a tmpfs set to 50%, and later on I add or remove RAM, does tmpfs automatically adjust its partition size? Also what if I have multiple tmpfs each set at 50%. Do multiple tmpfs compete ...
5
votes
2answers
166 views

1GB huge page - Is writing occurring in 1GB chunks?

I'm trying to understand the relation between huge page size and how data is actually being written to RAM. What happens when a process uses a 1GB huge page - does writing occur in 1GB chunks? I ...
1
vote
0answers
107 views

Xeon Phi swap from host's tmpfs

I want to use swap on Xeon Phi (mic0) using RAM from the host On the host: # free -m total used free shared buffers cached Mem: 129022 60312 ...
1
vote
4answers
8k views

How to clean up the RAM memory that is being used as cache memory?

My processor is using a big part of my RAM memory as cache and I want to clean it up because of that; will it prejudice something?
0
votes
1answer
76 views

Take copy of RAM

How trivial is it to take a copy of the current state of a Live Linux Distro's RAM storage? I have had situations where it might be useful to debug what caused a problem with the OS, and if I had ...
6
votes
1answer
278 views

How to have Linux wipe/randomize/sanitize RAM at shutdown?

For mysterious reasons I still double boot sometimes into Windows. My problem is that I fear that information may leak because the RAM memory is accessible to Windows. (the Linux partitions are ...
3
votes
2answers
116 views

Tool to force use FILE instead of RAM

I'm wondering why there is no such tool like ram2swap, similar to cpulimit in parts. E.g. There is program daemon.bin. Let's create temporary swap file ( 1 Gb ): % dd if=/dev/zero of=tmp.swap ...
3
votes
1answer
119 views

How to limit a user's RAM on Ubuntu? [duplicate]

I currently have a "friend" that has an account on my dedicated server which is running Ubuntu. Not getting into specifics, but he said he will use ~2gb max and he's using ~10gb. On to the question. ...
2
votes
3answers
483 views

Memory Mapping Linux 3+ kernel

Can some one help me understand how memory mapping is done Gone through this Why does Linux show both more and less memory than I physically have installed? but still i am not able to understand ...
1
vote
1answer
68 views

CPU and RAM monitorization by parent id

I'm trying to monitor the CPU and RAM usage (in % of total for example) of a given process wich may spawn several processes. The parent process is /bin/rscw so I get its pid by ppid_bl=$(ps -ef | ...
1
vote
0answers
142 views

Second RAM module is not shown in `free` in Manjaro

I have two RAM modules (8 GB each) but there is only one shown in free. I hope that following info will help you to locate the problem and find a solution: $ uname -srvmo Linux 3.10.27-1-MANJARO #1 ...
14
votes
1answer
2k views

Loading of shared libraries and RAM usage

I'm wondering about the way Linux manages shared libraries. (actually I'm talking about Maemo Fremantle, a Debian-based distro released in 2009 running on 256MB RAM). Let's assume we have two ...
1
vote
0answers
162 views

weird problem with 64 bit install and memory

I have a laptop with 8gb of RAM in two 4Gb slots, the processor is 64 bit compatible. However when I try to install 64 bit version of Linux (I tried, mint, arch, manjaro), it refuses to load the ...
3
votes
1answer
2k views

How to view RAM's SPD / timings table?

In Linux Mint, how to get the same information presented in the lower half of the below picture? Output by CPU-Z in Windows: What I've tried: Running CPU-Z 1.66 in Wine as Windows 95, 98 and XP. ...
9
votes
7answers
3k views

Processor usage increases with 4GB RAM installed

I have an Intel Atom D2700 (Synology NAS DS412+) with 4GB RAM running kernel 3.2.30 x86_64. This unit has a single DIMM slot. One thing I, and other's have found, is that when adding a 4GB DIMM ...
2
votes
1answer
3k views

htop reporting much higher memory usage than free or top

The following three outputs were taken essentially simultaneously: top: top - 02:54:36 up 2 days, 13:50, 3 users, load average: 0.05, 0.05, 0.09 Tasks: 181 total, 1 running, 179 sleeping, 0 ...
5
votes
1answer
2k views

Does kernel: EDAC MC0: UE page 0x0 point to bad memory, a driver, or something else?

kernel: EDAC MC0: UE page 0x0, offset 0x0, grain 0, row 7, labels ":": i3200 UE All of a sudden today, our CentOS release 6.4 (Final) system started throwing EDAC errors. I rebooted, and the errors ...
0
votes
0answers
65 views

Creating a fixed-size post boot block device from ram

First off: /root# cat /proc/version Linux version 3.12.6 What I'm trying to do is create a block device (no filesystem) out of ram of a fixed (configurable) size (pre-allocated, not ...
0
votes
0answers
26 views

Limit CPU/RAM usage per user? [duplicate]

I'm running game server applications on dedicated server that I have, but I want to be able to limit the CPU/RAM/etc usage on a per-user basis to make sure one of the servers doesn't eat up more ...