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7
votes
3answers
3k 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
21 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
76 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
214 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
93 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
49 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
34 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
18 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 ...
3
votes
1answer
66 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 ...
4
votes
2answers
75 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
55 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
0answers
41 views

EDAC (Error Detection And Correction) infrastructure in linux kernel

I am wondering how I can make use of the EDAC infrastructure in linux kernel. I have a i7-4600M CPU and I have compiled EDAC as a module in my kernel: --- EDAC (Error Detection And Correction) ...
1
vote
4answers
6k 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?
12
votes
1answer
6k 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?
0
votes
1answer
59 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
152 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 ...
2
votes
2answers
75 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
64 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. ...
1
vote
3answers
347 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
39 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
78 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 ...
11
votes
1answer
812 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
123 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
1k 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. ...
8
votes
7answers
2k 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 ...
0
votes
1answer
205 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 ...
1
vote
1answer
2k 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
958 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
47 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
24 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 ...
1
vote
2answers
234 views

TLB cache flusing when a page is swapped out

I recently heard that Linux simply flushes the TLB cache when the corresponding data in that physical address is swapped out, resulting in underutilization of the TLB. I don't know whether all OSes do ...
1
vote
0answers
15 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 ...
5
votes
2answers
264 views

How to create a fixed size Linux ramdisk which does never swap to disk?

I want to create a fixed size Linux ramdisk which never swaps to disk. Note that my question is not "why" I want to do this (let say, for example, that it's for an educative purpose or for research): ...
3
votes
3answers
4k 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 ...
0
votes
3answers
173 views

How much swap space should I use? [closed]

What rules should I follow to determine how much swap space my linux-based computer should have today?
15
votes
2answers
3k views

How to blacklist a correct bad RAM sector according to MemTest86+ error indication?

MemTest86+ (the version included with Ubuntu 13.04) says Failing address: 002f796c48 - 759.5 MB What should I specify in the memmap kernel parameter to bypass this area? I've tried running ...
6
votes
3answers
1k views

Is there a way to speed up boot time by loading things into RAM immediately?

I'm looking to lower my boot time by whatever means possible. I have about 8GB of RAM in my laptop, and if there's any way I could leverage that into faster boot time, that'd be awesome. Is there a ...
0
votes
0answers
82 views

What does it mean to redirect /dev/console through a non-existent file?

I have been trying to follow the "NAND firmware update" tutorial and I am perplexed by these last lines: now, in second stage, all processes are gone, only /dev/console in old root is still open ...
0
votes
0answers
32 views

Allocating more than 1 GB DMA memory

Is it possible to allocate more than 1 GB DMA memory on a machine, say with 24 GB RAM? If not, what makes it impossible?
0
votes
3answers
85 views

How to get data shown out of workspace or directly from application?

Because of some reason I had to use another web browser than my main which I use daily and I chose a small browser which I installed long time ago. This brower is called Dooble, version 0.07 ...
2
votes
1answer
177 views

Issues with grub badram

I have a stick of bad memory (the computer randomly segfaults an it gives memtest86+ errors, picture of output at bottom). As I would like this computer to be working while I work on getting new ram, ...
19
votes
3answers
3k views

How much RAM does the kernel use?

This question is motivated by my shock when I discovered that Mac OS X kernel uses 750MB of RAM. I have been using Linux for 20 years, and I always "knew" that the kernel RAM usage is dwarfed by X ...
10
votes
6answers
2k views

Can Linux “run out of RAM”?

I saw several posts around the web of people apparently complaining about a hosted VPS unexpectedly killing processes because they used too much RAM. How is this possible? I thought all modern OS' ...
1
vote
0answers
47 views

looking for name of a userspace tool for disk/network caching? [closed]

I remember seeing a blog post a month back that used a tool in the command which acted like a user space caching tool to buffer/cache reads and writes in RAM to overcome disk or network contention. I ...
1
vote
1answer
76 views

External Cache not socketed

When I check my CPU Cache with command dmidecode, I get Cache configuration to be Not Socketed. What does that mean? prayag@prayag:~/hacker_/draobkcalb$ sudo dmidecode -t cache # dmidecode 2.11 ...
0
votes
2answers
59 views

Is there kernel patch to prevent load files into RAM for LiveCD?

Is there kernel patch to prevent load files into RAM for LiveCD? I mean, if I'm use LiveCD with "boot to Ram" option, there is no needs for kernel to load executable binaries to RAM from RAM. It ...
0
votes
1answer
461 views

How to reduce buffers\cache

A monitoring system keeps alerting that my machine is reaching\breaking through it's RAM utilization threshold which is 15 GBs. I've done some reading and understood that the apparent RAM utilization ...
9
votes
2answers
1k views

How can I dump the full system memory?

After starting VirtualBox, the computer became sluggish and then hung completely due to OOM. Usually, OOM should be starting killing processes in order to free up some space, but this did not happen ...
0
votes
1answer
85 views

Crash analysis and 4 levels of page table

I am having xen 3.4.2 running with 15 vm (pv+hvm) on a host with 256 Gb RAM and 96 core CPU. But recently my host crashed on debug log its showing translating ffff83183fcb0000 with CR3 100ae42000 ...