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20
votes
4answers
13k views

Creating a ram disk on Linux

I have a machine with 62GB of RAM, and a trunk that's only 7GB, so I thought I would create a RAM disk and compile there. I am not a Linux expert. I found instructions on the internet to create the ...
17
votes
3answers
2k 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 ...
12
votes
2answers
2k 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 ...
10
votes
6answers
1k 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' ...
10
votes
1answer
226 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 ...
9
votes
1answer
2k 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?
8
votes
1answer
1k 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 ...
8
votes
2answers
707 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 ...
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 ...
7
votes
2answers
2k views

What is the appropriate value of vm.swappiness when using zram?

I'm using zram on my computer as a compressed RAM-backed swap. When the system needs to swap something out, swapping it to a zram-backed swap file is more or less equivalent to compressing that data ...
6
votes
3answers
6k views

64-bit Linux doesn't recognize my RAM between 3 and 32 GB

My problems were caused by a faulty memory module and quite possibly a broken kernel binary. I just now booted my PC with basically brand new hardware. I've been running Debian 6.0 AMD64 before, ...
6
votes
3answers
501 views

Preload movie on RAM

My current computer is unable to run FullHD movies smoothly and I was already resigned to the idea, because it seemed a graphics card issue, mine not being powerful enought to do the work (which is ...
6
votes
1answer
2k views

Tmpfs only with RAM

How to be sure that a tmpfs filesystem can only deal with physical and it's not using a swap partition on disk ? Since i have a slow HDD and a fast RAM i would like, at least, giving higher priority ...
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 ...
5
votes
2answers
1k views

How to get top 5 most ram intensive applications from Bash?

So I look at avaliable to me servers load and see that some other user has created some really ram intensive app that kills my server hosting abileties. I wonder what is bash command to get top 5 ...
5
votes
2answers
149 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): ...
5
votes
3answers
2k 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 ...
5
votes
1answer
100 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 ...
4
votes
1answer
3k views

Move /tmp to RAM

I am trying to move /tmp to RAM and obey good practice: /var/tmp should NOT be placed in tmpfs, as it must survive reboots not mount /tmp as a stand-alone tmpfs, but rely on /dev/shm or /run/shm ...
4
votes
1answer
657 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 ...
4
votes
1answer
94 views

Is it possible to lock bad bits in RAM on Linux?

Recently I bought 8 GB of RAM and it has bad bits. Is it possible to lock the bad bits to make Linux avoid them?
4
votes
1answer
242 views

Limit disk buffer usage in SLES 11SP2 to allow more efficient memory overcommit on esxi host

When running VMs on an ESXi host, you can overcommit the memory. Example: host == 20GB physical RAM The amount of RAM allocated to each VM is VM1 == 10gb VM2 == 10gb VM3 == 10gb VM4 == 10gb The ...
3
votes
2answers
189 views

Shouldn't there be more RAM free than this? [duplicate]

Possible Duplicate: Correctly determining memory usage in Linux I see that almost all my RAM is in use. Is this bad? Strange thing is I don't see what is actually using the RAM.
3
votes
2answers
59 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
747 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. ...
3
votes
2answers
510 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?
3
votes
1answer
45 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. ...
3
votes
1answer
1k views

Is it possible to run any distro from RAM from within an .iso saved on an NTFS file system?

Running entirely from RAM been done on various distros such as Slax, DamnSmallLinux, and newer Ubuntu versions, and since I have 8GB it seems reasonable that I could run many distros entirely from RAM ...
3
votes
0answers
189 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. ...
2
votes
2answers
684 views

How much RAM can an application allocate on 64-bit x86 Linux systems?

Is it true that a single application can not allocate more than 2 GiBs even if the system has GiBs more free memory when using a 32-bit x86 PAE Linux kernel? Is this limit loosened by 64-bit x86 Linux ...
2
votes
3answers
937 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
316 views

Linux Mint Stops Network File Transfers to Load Data into RAM

I've never seen or heard anything like this before, and I can't find anything else online that is at all similar. I've upgraded my network to gigabit and have been transferring large files lately ...
2
votes
1answer
108 views

Can't Get “lsdvd” To Work On Remastered Live CD's

I have attempted to make Tiny Core Linux, Archboot (didn't get very far), and SliTaz remastered live CD's with lsdvd included, in order to create a lightweight transcoding solution that allows as much ...
2
votes
0answers
276 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
1answer
120 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, ...
1
vote
4answers
4k 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?
1
vote
4answers
6k 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.
1
vote
3answers
189 views

CPU or RAM better in old machine?

I'm planning to use one of two old computers as a low-volume backup server. The machine will be online and files will be backed up over ssh/rsync. I will do a minimal install of Ubuntu or Debian ...
1
vote
1answer
65 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 ...
1
vote
2answers
253 views

RAM size and SWAP size

I want to know why the swap partition have to more double size the RAM Size ? for example if the ram installed in machine 64 G.B , the swap have to be 128 G.B ?
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 ...
1
vote
1answer
78 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
2answers
203 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
1answer
497 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 ...
1
vote
1answer
19 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
32 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 ...
1
vote
0answers
76 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 ...
1
vote
0answers
13 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 ...
1
vote
0answers
44 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 ...
0
votes
3answers
86 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?