Tagged Questions

2
votes
0answers
64 views

Linux: Total swap used = swap used by processes +?

So, I'm trying to do some investigation on where does swap use come from in a system with high swap usage: # free total used free shared buffers cached Mem: ...
2
votes
2answers
99 views

Where is the virtual memory stored on hard drive?

If a process wants to access a memory address that is not in physical memory, the OS outsources a page frame from physical memory to the hard drive for later use. Where on the hard drive is this data ...
0
votes
2answers
91 views

swap partition and its laws

I remember for choice of swap partition, we should use (swap > 2xRAM) at least.Of course it deprecated , because max of computer's ram is very high. kernel support it. My question: i remember each ...
1
vote
2answers
108 views

Is it a bad idea to not have a swap partition on an embedded linux setup?

I have a small embedded linux kernel and file system created via buildroot that is installed onto a compact flash drive running on an x86 board. I am using an initramfs (due to power loss concerns) ...
2
votes
2answers
222 views

How do I configure systemd to activate an encrypted swap file?

My previous question produced the commands to add an encrypted swap file: # One-time setup: fallocate -l 4G /root/swapfile.crypt chmod 600 /root/swapfile.crypt # On every boot: loop=$(losetup -f) ...
6
votes
1answer
276 views

How do I set up an encrypted swap file in Linux?

How do I set up an encrypted swap file (not partition) in Linux? Is it even possible? All the guides I've found talk about encrypted swap partitions, but I don't have a swap partition, and I'd ...
1
vote
1answer
95 views

Which processes swaps memory

I can see swap's total, used, free etc. sizes from top command. But I can't figure out which process uses swap, is it possible to find out swap memory by process? I'm running CentOS 6.3.
4
votes
3answers
1k views

Swap usage too high?

I have a debian sid box, freshly installed about a month ago, with no desktop apps running at the moment. Any command I try to run (via ssh) makes the hard disk work very hard. The system worked ...
4
votes
2answers
312 views

Linux (3.4) SSD swap partition usage causes extreme latency - how to eliminate?

I'm running on 4G RAM with an extra 6G swap partition, SSD is a pretty decent SAMSUNG MZMPA128HMFU model. System responds very well to workloads when things stay in RAM, but as soon as things reach ...
2
votes
2answers
246 views

Does swap need to be on a contiguous LVM logical volume

I am setting up a machine to run a number of virtual machines. I am using a single HDD with a boot partition and an LVM partition. I read on the Arch wiki that logcial volumes which will be used for ...
0
votes
1answer
499 views

Drop_caches doesn't drop caches?

Sometimes I see my swap file is a bit bigger then usual. I tried sync && echo 3 > /proc/sys/vm/drop_caches to no avail. But when I tried swapoff -a it takes a bit longer but the swap file is ...
3
votes
1answer
335 views

What command can be used to force release everything in swap partition back to memory?

What command can be used to force release everything in swap partition back to memory ? Presume that I have enough memory.
5
votes
1answer
134 views

Can I accelerate swap by using multiple harddrives?

I still have two old ATA drives (one is only 8GB, one is somewhat defect) and I've been thinking about putting them into my PC and activating swap on them, too. What will be effect of this? Will my ...
4
votes
2answers
490 views

Linux running slow with 0 swap left

Our Linux server is responding very slowly. top doesn't show any excessive CPU usage. I noticed that even though there's about 5GB of free memory, the system is using all of swap with no free swap ...
2
votes
4answers
751 views

How to reduce size of swap after a system is already installed?

I'm running Debian Squeeze 6.0.5. Does the use of swap memory make my computer run slower? If so, how can I reduce the size of the swap memory after the system is already installed?
2
votes
1answer
462 views

Is it possible to trigger OOM-killer on forced swapping?

Is it possible to have the system preemptively swap out inactive pages (vm.swappiness), but invoke the oom-killer when the system runs out of RAM (as opposed to running out of memory) and is forced to ...
1
vote
1answer
131 views

Swap Utilization Increase with Oracle Coherence

We are using Oracle Coherence on linux servers. However, we noticed that because of Coherence processes running, often our swap utilization % increases too much, sometimes becoming more than 98%, even ...
2
votes
1answer
372 views

KVM and swap problem

So I have a problem, I'm managing a server and the swap partition is way too small at the moment. The machine runs KVM with about 24 VM's on it. The problem is that some of them are rather inactive so ...
2
votes
1answer
395 views

tmpfs and vm.swappiness

I have started tuning a bit Linux VM performance on my system (yes. I know that vm.swappiness=0 will kill kittens but I found 30-40 as much better for me as it improved my latency - probably at cost ...
7
votes
1answer
928 views

What does the vm.swappiness parameter really contol?

Per the kernel documentation: This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase agressiveness, lower values decrease the amount of swap. ...
0
votes
1answer
289 views

LinuxMint, unable to set swap partitions to equal priority

I only recently realised that you can specify multiple swap partition, spreading them across drives. Well that's great for me as my desktop system often uses swap space and I have three different ...
4
votes
2answers
4k views

Cleancache vs zram?

I have an old laptop here with only 512 MB of RAM. Since a few kernel releases, I am using zram to convert 256 MB of it to a compressed ramdisk which is then used as swap. This has proved to be very ...
5
votes
2answers
1k views

How to set up properly zram and swap

I'm configuring & compiling new 3.0 kernel. One of the goodies I planned to use for some time (by patching) that was merged into 3.0 is zram. Is it possible to set both hdd swap and zram swap so ...
10
votes
1answer
978 views

per process swapiness for linux

/proc/sys/vm/swappiness is nice but i want a knob that's per process like /proc/$PID/oom_adj so that i can make certain processes less likely than others to have any of their pages swapped out unlike ...
8
votes
4answers
3k views

how to “unswap” my desktop

If my desktop run out of memory and swaps a lot then I free or kill the application wasting my RAM. But, after that, all my desktop/applications have been swapped and are horribly slow, do you know a ...
2
votes
1answer
191 views

How to reuse Physical memory in the absence of swapping?

How can I reuse physical memory in the absence of swapping?
17
votes
3answers
3k views

Why does Linux use a swap partition rather than a file?

It seems to me a swap file is more flexible.
6
votes
1answer
4k views

How to test swap partition

I'm trying to diagnose some random segfaults on a headless server and one thing that seems curious is that they only seem to happen under memory pressure and my swap size will not go above 0. How can ...
5
votes
3answers
865 views

How can I tweak the kernel for total swap out?

I would like to deploy the following swapping policy: By default all pages in memory should also be in swap space. When a page in memory is changed (i.e. dirty), the page should be written out as ...
24
votes
12answers
2k views

How can I tweak my Linux desktop to be more responsive?

I have the experience that Linux works fine until the physical memory is exhausted. As soon as swap space is used the performance is severely degraded and the GUI becomes unresponsive. This problem ...