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Questions tagged [memory]

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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7answers
9k views

Get chrome's total memory usage

Since google chrome/chromium spawn multiple processes it's harder to see how much total memory these processes use in total. Is there an easy way to see how much total memory a series of connected ...
0
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1answer
277 views

Linux Debian memory leak? [duplicate]

I am running an application which needs to be restarted everyday. I am noticing that when I close this application and I run "free -m" It says: total used free shared ...
2
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0answers
20 views

How to enumerate memory used and reserved by kernel and drivers

I am running two VMs (Ubuntu 18.04), both with 0.5 GiB of memory. One is on AWS and one is on Azure. I found that despite both systems having 512 MiB of memory, the AWS system has 479 MiB of usable ...
179
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12answers
144k views

How to fill 90% of the free memory?

I want to do some low-resources testing and for that I need to have 90% of the free memory full. How can I do this on a *nix system?
2
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1answer
22 views

How to disable memory for a NUMA node on a Linux system

Is there a way to disable access to memory associated with a given NUMA node/socket on a NUMA machine? We have a bit of controversy with the vendor about our HP DL560 machines. The sales type’s ...
0
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1answer
14 views

low and high watermarks seem higher than predicted by Documentation/sysctl/vm.txt

Motivation I wrote an answer here: How large are the "watermark" memory reservations on my system? The "min" watermark for the "Normal" zone appeared as 31449 pages. This is 125796 ...
1
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1answer
20 views

Why is “Unevictable” memory larger than “Mlocked” memory?

Why is "Unevictable" memory larger than “Mlocked” memory? $ cp /proc/meminfo meminfo $ grep -iE "lock|evictable" meminfo Unevictable: 161436 kB Mlocked: 12772 kB $ uname -r # My ...
0
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1answer
16 views

Active(anon) + Inactive(anon) is more than AnonPages

$ grep -iE 'anon' /proc/meminfo Active(anon): 2962828 kB Inactive(anon): 1039836 kB AnonPages: 2599436 kB AnonHugePages: 0 kB Q1. Assuming there are zero "huge pages", do you know ...
3
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1answer
136 views

How large are the “watermark” memory reservations on my system?

swappiness This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase aggressiveness, lower values decrease the amount of swap. A value of ...
0
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1answer
15 views

Why is my min_free_kbytes larger than the documented calculation (and larger than the documented maximum)?

My machine has roughly 8GB of RAM. Why is min_free_kbytes set to 67584? The kernel code comment says I should expect to see min_free_kbytes set to around 11584. It also says the largest it would ...
0
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0answers
20 views

Memory Issue and getting OOM

Linux total memory is full but not showing any usage by any process but getting OOM ,how to troubleshoot this ? free -m total used free shared buffers cached Mem: ...
3
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1answer
88 views

Why are some caches not droppable?

Here's the output of free -m: total used free shared buff/cache available Mem: 421 158 153 39 109 195 Swap: ...
0
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1answer
30 views

What is the 3.5 GB of <anonymous> memory usage in this system, that is not “[heap]” (666M)?

$ sudo smem -t -m > m; head -n5 m; echo; tail m Map PIDs AVGPSS PSS /dev/dri/card0 2 0 0 /dev/shm/org....
10
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1answer
679 views

Is “Cached” memory de-facto free?

When running cat /proc/meminfo, you get these 3 values at the top: MemTotal: 6291456 kB MemFree: 4038976 kB Cached: 1477948 kB As far as I know, the "Cached" value is disk ...
0
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1answer
32 views

Can user space memory make the system go haywire?

So I was reading How Linux Works by Brian Ward. In it, he says, the user-space applications going bad will not wreck the system. Figure 1-1. General Linux system organization There is a critical ...
0
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0answers
22 views

how to make sure Ubuntu 16.04 use swap only when memory is truely used instead of full of cache?

I have already set vm.swappness to 0, but the system still uses swap after sometime the rest of memory is filled by cache. This leads to high load and high latency, probably because I put SWAP and the ...
9
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1answer
6k views

Tracking down “missing” memory usage in linux

On an Arch 3.6.7 x86_64 kernel I am trying to account for the memory usage of the system, which the more I look at it, the more there appears to be a hole (in the accounting of used memory, a non-hole ...
1
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1answer
2k views

How can I manually trigger the virtio balloon driver on a guest?

I would like a certain Linux guest running in QEMU to release memory before the host is under memory pressure. How can I manually trigger the virtio balloon driver on a guest so that it releases as ...
0
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1answer
19 views

cairo graphics inside my_conky.lua is eating memory when I use surface_create_from_png

I tried adding images to my conky.lua with the following function function drawimage(cr,img) image = cairo_image_surface_create_from_png (img) cairo_set_source_surface (cr, image, screen.x, ...
3
votes
1answer
194 views

How does Linux make sure to reclaim useless “buffers”, from caching the ext4 journal writes, before anything else (e.g. before swapping at all)

My laptop tends to run with about 256MB counted as "Buffers" - in /proc/meminfo and free -w -h - out of about 8GB of RAM. I'm interested in memory usage. I sometimes get into trouble using too much. ...
0
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0answers
27 views

when dirty page state is changed to clean?

When I study page cache and writeback(flush dirty pages to storage), the one question came up to me. When process makes too much dirty pages, writeback thread(background thread) will flush dirty pages ...
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0answers
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Why /proc/status and /proc/smaps RSS value is different?

If I sum up all Rss fields in /proc/smaps I never get the same result as VmRss field in /proc/status Who knows why this happens? Which value is true RSS? Example: cat /proc/16004/smaps | grep -P '...
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3answers
29k views

What do the “buff/cache” and “avail mem” fields in top mean?

Within the output of top, there are two fields, marked "buff/cache" and "avail Mem" in the memory and swap usage lines: What do these two fields mean? I've tried Googling them, but the results only ...
7
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2answers
113 views

How does the ELF loader determine the initial stack size?

I'm studying the ELF specification (http://www.skyfree.org/linux/references/ELF_Format.pdf), and one point that is not clear to me about the program loading process is how the stack is initialized, ...
1
vote
2answers
56 views

Why does Linux, by default, overcommit memory?

Related to the SuperUser question at https://superuser.com/questions/200387/linux-overcommit-memory my question is what was the reason why they made to allow overcommit the default? Since 2.5.30 ...
9
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1answer
477 views

Why can't I “swapoff” when there's plenty of memory?

I've recently noticed that even though there's a lot of memory on my system: # free -m total used free shared buffers cached Mem: 15965 9680 ...
2
votes
0answers
960 views

Slab cache affecting used memory much more than /proc/meminfo suggests

I'm dealing with a memory issue that is affecting hundreds of machines in AWS. They are i3.4xl instances with 120GB of RAM. There is a Java database server running inside a Docker container that ...
2
votes
0answers
57 views

Is this a kernel memory leak? (Excess Active/Inactive pages v Cache)

I have a machine that leaks memory (even after an application restart) - two machines run similar applications with similar workloads, slightly different kernel revisions of 4.x The noticeable ...
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1answer
70 views

“buff/cache” is very high, how I can free it? [duplicate]

The output of the top command shows that 29GB of memory is used by "buff/cache". What does it mean and how I can free it? It is near to 90% of memory.
1
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1answer
1k views

Compiled kernel 4.19 will not boot: “Kernel panic not syncing : System is deadlocked on memory”

I am compiling kernel 4.19 on Ubuntu 14.04 because I have a assignment to add a system call, but when I try to boot this kernel there's a error: Kernel panic - not syncing: System is deadlocked on ...
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0answers
24 views

atop shows `swout` (swapping) when I have gigabytes of free memory. Why?

Why did atop show that I was swapping out over 20,000 pages - over 80 megabytes - when I had gigabytes of free memory? atop refreshes every ten seconds. Each refresh shows the activity since the ...
4
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2answers
2k views

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).
0
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2answers
26 views

Linux Memory Allocation/De-allocation

will the pgfree/s command happen without pgscand/s? How and what is the difference between pgfree/s and pgscank/s?
0
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1answer
81 views

transmission-daemon: UDP Failed to set receive / send buffer

I just compiled the transmission{-daemon,-cli} on my Debian 10 Buster, and installed it with some minor and major problems. One of those minor ones is apparent failure to set UDP receive buffer / ...
82
votes
7answers
295k views

How to find which processes are taking all the memory?

I'm looking for somthing like top is to CPU usage. Is there a command line argument for top that does this? Currently, my memory is so full that even 'man top' fails with out of memory :)
2
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1answer
73 views

82MB of “reserved memory” on 512MB (x86) system

I reinstalled a fresh debian 10 on an old x86 system with 512MB RAM (everything works ok). Available memory is 431MB. (No graphic card plugged right now) I don't think that that much memory was "...
0
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0answers
29 views

Report memory usage (systemd)

We have several running cronjobs on our linux system (systemd). When I issue the command: systemctl status .service then I see correctly the usage (in this case only the CPU usage (I still need to ...
147
votes
6answers
209k views

Limit memory usage for a single Linux process

I'm running pdftoppm to convert a user-provided PDF into a 300DPI image. This works great, except if the user provides an PDF with a very large page size. pdftoppm will allocate enough memory to ...
10
votes
2answers
2k views

30% of RAM is “buffers”. What is it?

$ free -h total used free shared buff/cache available Mem: 501M 146M 19M 9.7M 335M 331M Swap: 1.0G ...
116
votes
6answers
120k views

How do I determine the number of RAM slots in use?

I forgot how many RAM modules are installed on my laptop. I do not want to unscrew it but want to look it up on the console using bash. How do I gather this information?
2
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3answers
2k views

What is paging space in AIX?

I get that Paging Space in AIX is actually like SWAP in Linux. In one of my AIX servers at work, i'm actually seeing 99.7% Physical memory being utilized when my application is running(handling quite ...
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1answer
1k views

Where does the Linux kernel reside in memory ?

From some book I have, I have in my notes that the Linux kernel resides at 0xc00000000 on 32-bit systems, and is mapped into user space for performance reasons. Is this accurate ? How can I verify ...
1
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1answer
3k 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: ...
4
votes
2answers
2k views

Huge page and performance improvemnt

How can using huge page improve performance? I have read that huge pages improve performance by reducing TLB lookups and reducing the size of the page table. Can someone tell me how this helps with ...
0
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1answer
13 views

whonix qemu/kvm maximum memory usage

I am using the newest Whonix on qemu/kvm. Why is the memory usage always at Maximum for W-Gateway (max 2024 MiB) and W-Workstation (4048 MiB)? I have other VMs (debian) installed as well, and it is ...
0
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1answer
26 views

top command, why such a big difference between VIRT and RES, while swap is 0?

I've read some posts that says a process's VIRT = RES + SWAP. But look at the screenshot below, the whole system's Swap is 0 (0 used). So I expect each process's VIRT at least ≈ RES. But as you can ...
2
votes
1answer
44 views

Difference between CONFIG_RANDOMIZE_BASE and CONFIG_RANDOMIZE_MEMORY in Linux kernel config

This page says that RANDOMIZE_BASE is for KASLR and it randomizes the physical AND virtual addresses which is obvious in 32-bit and comprehensible in 64-bit. But what does RANDOMIZE_MEMORY do exactly?...
0
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0answers
26 views

Total memory vs memory per CPU vs memory per process

I have troubles understanding memory (RAM) specifications of CPUs. Just as an example, the Xeon Gold 6144 specs give a maximal memory size of 768GB. If I have a mainboard with two CPU sockets and 24 ...
0
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1answer
22 views

Why does `dd` map 200M of virtual address space?

sudo atop -R dd if=/dev/zero of=/dev/null # in a background tab In atop, type m for memory details. Type /dd to search for dd. Result: PID TID MINFLT MAJFLT VSTEXT VSLIBS VDATA VSTACK ...
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4answers
6k views

How much RAM needed for preventing use swap?

At my system always available some "Free" and "Inactive" memory, but sometimes system move couple megabytes to swap. Per night it maybe around 100MB, but for a few days in swap could be more than ...