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

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FDT relocated by U-Boot cannot be accessed by Linux (in highmem)

We run a customized version of U-Boot on an ARM-based embedded system and would like to load Linux 4.3 with a device tree blob. The system features 1GB of RAM of which the top 128MB are reserved for ...
5
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1answer
71 views

Is forcing an application to release some the allocated memory possible?

Ever since I came back to Firefox a year or so ago I have been facing the same issue over and over again - the browser just keeps eating up my memory. The problem arises from (maybe the incorrect ...
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2answers
30 views

Swap used even though most memory is “cached”? [duplicate]

I'm trying to make sense of this free -m output: total used free shared buffers cached Mem: 7971 7608 363 1 17 4703 ...
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2answers
132 views

How much RAM should an SSH connection typically use?

I'd like to ask about how much memory an SSH connection should take typically. Here is how I'm finding out how much of a RAM hit is incurred: Kindly don't get vehement that I'm using a GoDaddy shared ...
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1answer
47 views

Redhat: Swap Memory Used is Much Higher Than Total

The top command showed the following information: Mem: 132110132k total, 10447536k used, 121662596k free, 76120k buffers Swap: 16777212k total, 18446744063504593392k used, 10221735436k free, ...
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32 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 ...
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1answer
60 views

determine the actual memory usage of several processes that share a large memory segment

I just took a look at the output of top and it showed me (amongst other processes) the following: As once can see I have ten processes consuming approx 10GB each so 100GB in total. The computer ...
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16 views

PDOException: SQLSTATE[HY000]: General error: 23 Out of resources when opening file xxxx.MYD' (Errcode: 24) [duplicate]

I am getting this error message when trying to access a php page: PDOException: SQLSTATE[HY000]: General error: 23 Out of resources when opening file xxxx.MYD' (Errcode: 24) How can I solve this ...
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2answers
63 views

Does Linux keep programs in RAM after 1 execution?

I read somewhere that Android/Linux keeps programs in working memory after they close so that when they're opened later then they can be opened faster. Is this true? If it is not, is there a way to ...
2
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0answers
31 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?
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1answer
32 views

Retrieve data from mem cache

Newbie to Linux. My application writes to a log file and for some reason it stopped writing to that file suddenly. We have restarted the application to fix this glitch. Is it possible to retrieve the ...
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225 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 ...
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17 views

finding gyroscope memory location

How can I find the memory location of the gyroscope data for my machine? this tutorial provides a memory address for a specific device. How can I figure out what my memory location should be? I am ...
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1answer
53 views

What is page fault and when does it occur? [closed]

In an interview I was asked this question: what is a page fault and when does it happen?
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2answers
180 views

how to deallocate /dev/ram0

I have allocated /dev/ram0: dd if=/dev/zero of=/dev/ram0 bs=1M count=1024 Now I have 1Gb sitting in memory. How do I free up the allocated space ?
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86 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 ...
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1answer
53 views

Monitoring GPU memory I/O

Is there any way to monitor GPU memory I/O from the shell, with Nvidia graphic cards used with CUDA? I use nvidia-smi to see the current memory utilization, but I would prefer to see the deltas ...
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36 views

My SLES 11 uses 6 GB RAM while nothing is running. How can I find out what is needing it? [closed]

Can anybody tell me what is consuming that much memory on my SLES 11 SP3 server? I suspect a serious bug in the kernel that it does not release memory allocated by an application once it quits. This ...
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1answer
46 views

Can I mark _current_ memory contents as non swappable?

Background: in my linux (ubuntu) workstation, I want to run some experiments that allocate more memory than the physical RAM while I do other 'normal' stuff in the GUI. Problem: I have plenty of ...
3
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1answer
84 views

Creation of the heap region/segment in Linux

It's my understanding that on Linux the process loader doesn't automatically create a "heap" region for a process like it's the case for the stack, is that correct? I used /proc/$$/maps and before ...
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103 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 ...
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35 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 ...
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1answer
162 views

How to interpreted top/htop memory usage

I have a htpc/server-ish ubuntu box running at home with kodi (xbmc) and some other webservices. I noticed kodi was laggish and ssh'ed into the box to see what was going on. I saw this htop output: ...
3
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1answer
219 views

Is there a way to know how much memory Linux Os is using?

I am looking for a way to know the size of the memory that Linux os is using (I'm not worried about the other applications memory size). I am using Ubuntu distribution (Ubuntu 15.10). Thanks for your ...
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2answers
167 views

How to identify cause of large buffer memory usage?

I have a production machine running a 2.6 kernel (Centos 6.7) with 64 GB of RAM of which 18 GB is apparently used for buffer memory. I am interested in identifying specifically what that 18 GB is ...
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170 views

Is it possible to impose some kind of soft limit on the memory consumption of processes?

I reckon it's not such an uncommon problem: one process allocates massive amounts of memory (be it due to a memory-leak bug, because you try to process an infeasibly large input file, or whatever). ...
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180 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 ...
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24 views

What does “wrap around” mean in DMA?

Recently working on a PCI driver project and trying to understand the Scatter Gather DMA. In my project, the PCI device(in a PC's PCI slot) is the DMA master and I want to do a DMA write to the PC's ...
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2answers
126 views

Is there a way to free memory? [duplicate]

I remember, back from my days with Windows Vista/7, that there was a tool called memclear or memclean that would free some memory by invoking the NT garbage collection API. Probably it cleared cache ...
2
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1answer
101 views

Does my system use all available RAM?

I installed 16GB of RAM on a motherboard that shouldn't take it. Should I buy a better motherboard or change anything at all? It seems to be working fine. Memory: Crucial Ballistix Sport "(8GBx2) ...
0
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1answer
57 views

How to find hugepage size on system?

I am getting following two different result. which one i should consider for Hugepage? [root@server ~]# getconf PAGESIZE 4096 [root@server ~]# grep -i hugepagesize /proc/meminfo Hugepagesize: ...
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Why is the size of “/proc/kcore” file so bigger than the physical memory size?

From proc manual: /proc/kcore This file represents the physical memory of the system and is stored in the ELF core file format. With this pseudo-file, and an unstripped kernel ...
2
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1answer
668 views

How to find out how much memory lxc container is allowed to consume?

I'm trying to make ansible set InnoDB buffer pool size to some percent of available memory. But ansible_memtotal_mb and free report how much memory the host has. How do I figure out how much memory is ...
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23 views

Best small distro for ROM burning of the system for an embedded system

I am building a specific device and I would like to know what Linux based small distribution would be good when I would choose the put-Linux-on-the-ROM route, so, that the system is not possible to ...
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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?
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2answers
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What's the difference between ioremap and file operation mmap?

I'm currently working on a PCI device driver for Ubuntu. I have some example code about PCI driver, but I have difficult on understanding the ioremap and file_operation.mmap. The description of file ...
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43 views

how to enable 1MB dma-kmalloc

I'm running a ubuntu 15.10 VM and testing code that will allocate 1MB dma buffers. However, from the /proc/slabinfo, the max that can be allocated is 8K dma-kmalloc-8192 0 0 8192 4 ...
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1answer
27 views

What is taking up my memory in my Linux virtual machine

I'm trying to debug an application (mongodb) memory usage on a a virtual machine. mongod, is taking 11% of memory. I know this by using top but when I want to see how much of my 7.5GB is free, I ...
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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: ...
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2answers
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What tools can I use to diagnose the exact reason for laptop slowness? And how do I use those tools?

I am running Linux Mint 17 on my laptop. When using applications (mainly Web Browsers) the machine freezes for little time periods. The CPU indicates 100% usage at such times, but this only seems to ...
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246 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 ...
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240 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 ...
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74 views

Where is my memory being used?

Only 28G is being used by buff/cache. $free -h total used free shared buff/cache available Mem: 188G 87G 72G 17M 28G ...
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1answer
147 views

How do you prevent system from freezing when memory is used up?

I've been running a process (gdb) that can easily use up all my ram and swap space. Every time that happens the whole system becomes very non-responsive and Xorg will barely update, I can't swith to ...
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1answer
46 views

How do I check how much total memory my VM has? [closed]

I've tried /proc/meminfo but my permission has been denied.
3
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1answer
200 views

What is the usual Allocation unit for a process on Linux?

I'm currently studying memory management in Operating Systems. Allocation Unit is the smallest unit of memory the OS will give to any process. I've read in this page, in the 'Memory allocation ...
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1answer
2k views

find: cannot fork: Cannot allocate memory

I want to delete 1 file at a time from my directory which contains so many files,So i want to remove 1 file at a time. Just to avoid too many reads and failed at too many arguments. find ...
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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: ...
3
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1answer
80 views

Shared memory v/s physical memory

I have a C++ process which is using shared memory to store and transfer data between its child processes. I want to check the shared memory usage while the parent process is executing just like top ...
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1answer
277 views

How can two identical virtual addresses point to different physical addresses?

Following a fork() call in Linux, two processes (one being a child of the other) will share allocated heap memory. These allocated pages are marked COW (copy-on-write) and will remain shared until ...