Swap space is an area of the hard disk that serves as an overflow when the computer memory is full. The memory used by inactive applications is partially written out to disk to make room for other applications and for the disk cache for active files.

learn more… | top users | synonyms (1)

3
votes
4answers
4k 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?
1
vote
2answers
3k views

free / top difference. Does free show virtual memory?

free -m shows me the following in my system: total used free shared buffers cached Mem: 3954 3842 111 0 248 2585 -/+ ...
4
votes
2answers
923 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
251 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
789 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 ...
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 ...
26
votes
7answers
1k views

Is swap an anachronism?

I've used unix for quite a while, and for the last couple years I've felt like swap is an anachronism, but I'd be curious what other folks think. My argument is roughly this (assuming no global ...
2
votes
1answer
608 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 ...
19
votes
3answers
3k views

What does the vm.swappiness parameter really control?

Per the kernel documentation: 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. ...
3
votes
2answers
509 views

Java process, swap (/proc Solaris10) memory highly utilized

How can I analyze high swap memory utilization of Solaris 10 for Java processes?
0
votes
1answer
416 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 ...
0
votes
1answer
900 views

Zram does not start at start-up

I am using pinguyos 11.10. Pinguyos is a variant of Ubuntu 11.10. I have installed zram like this: sudo add-apt-repository ppa:shnatsel/zram sudo apt-get update sudo apt-get install zramswap-enabler ...
20
votes
4answers
29k views

How to completely disable swap?

I am using Debian sid, hard drive formatted with ext4, running on linux 3.1 I remember on previous linux versions (maybe before 3.0), if I run out of memory, and swap is not enabled, programs will ...
3
votes
1answer
309 views

Is there an in-memory compressed swap facility (like Compcache) for FreeBSD?

Is there anything like CompCache for FreeBSD?
3
votes
1answer
978 views

Command for swap info in HPUX itanium and HPUX PARISC?

I need to get commands for swap information in HPUX (both Itanium and PARISC) somebody please help.
1
vote
1answer
1k views

How to re-enable hibernate in Kubuntu 11.10?

After making some changes to my swap space, namely deleting and recreating swap space, my Kubuntu 11.10 has lost hibernate functionality. Although the button has returned, hibernating only appears to ...
16
votes
2answers
11k views

How can I check if swap is active from the command line?

How can I check if swap is active, and which swap devices are set up, on the command line?
7
votes
3answers
5k views

Where to put swap space, at beginning or end and other swap questions

Where do I put my swap? Debian installation gives 2 choices: (1) at the end or (2) at the beginning of the disk space. What is optimal? What is the optimal amount of swap given my computer has ...
2
votes
2answers
504 views

Does mkswap check that a partition is a swap partition before formatting it?

I checked the man page for mkswap and was left confused whether mkswap tests whether a partition is of type 82 before formatting it. Background: I am using Ubuntu 11.04, and I had just set up my swap ...
3
votes
1answer
921 views

Solaris swap allocation with mlocked shared memory

I'm having a hard time understanding how Solaris 10 x86 swap allocations work in the presence of mlocked share memory. I wrote a small program that: Gets a 1G SHM segment (shmget) Attaches it to ...
1
vote
1answer
467 views

Is there a way to kick kswapd and make it swap out pages?

Even though I have set swappiness to 100 and enabled swap, nothing is being swapped out. This is probably because I don't have high memory pressure at the moment. For testing purposes though, I want ...
2
votes
1answer
1k views

Mysql / swap space full

I have MySQL Ver 14.12 Distrib 5.0.45 server running on Multiflex Intel Blade having 8G of RAM & 8 x Intel(R) Xeon(R) CPU E5410 @ 2.33GHz. The problems I am facing are: For the last 3-4 days ...
5
votes
2answers
5k 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 ...
6
votes
3answers
2k 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 ...
3
votes
1answer
525 views

What are the advantages of swap on a raid-1 (mirror) device?

What are the advantages of swap on a raid-1 (mirror) device? (in a server environment running linux) I mean, you can just use multiple disk devices in linux for swap. And with swap devices that have ...
14
votes
1answer
2k 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 ...
1
vote
1answer
651 views

What is excessive swapping

This post led me to ask that question. Cache contention On a large site, if you are using MyISAM, contention occurs in the database tables when the cache is forced to clear after a node ...
13
votes
4answers
5k views

How to re-load all running applications from swap space into RAM?

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 ...
23
votes
3answers
7k views

Are there any side effects when two distros share a swap partition?

In order to save disk space, I want to have two OS installations share a single swap partition (a dual-boot). Is this a good idea?
2
votes
2answers
233 views

How to reuse Physical memory in the absence of swapping?

How can I reuse physical memory in the absence of swapping?
2
votes
3answers
2k views

How is paging managed in the absence of swapping?

How is paging managed in the absence of swapping. If that is the case, how will a page fault be managed? What I meant is, if there is no availability for swapping, then how is Paging managed. I ...
10
votes
1answer
528 views

What happens to data in swap when your computer hibernates?

When a computer goes into hibernation mode, it saves the contents of the RAM into the swap space so that it can resume exactly where it left off when it powers back on. So, what if you are currently ...
4
votes
6answers
6k views

What is the use/meaning of 'swap area' while linux installation?

When i installed ubuntu in my x86 machine, I had to configure some memory as 'swap area'. What is the use of this memory and what is the importance of this memory in linux file systems? How can I ...
9
votes
1answer
6k views

swapon: Operation not permitted

I'm running this as root, obviously. I've created a file called /swap/sw1, by dumping 512 megs of /dev/zero into it. I then ran mkswap, which said: Setting up swapspace version 1, size = 524284 KiB ...
74
votes
7answers
20k views

Why use swap when there is more than enough RAM

Using swap space instead of RAM can drastically slow down a pc. So why, when I have more than enough RAM available, does my Linux system (Arch) use the swap? Checkout my conky output below: ...
19
votes
3answers
5k views

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

It seems to me a swap file is more flexible.
9
votes
1answer
7k 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 ...
7
votes
3answers
504 views

Why does it makes sense to cache swap?

It sounds quite counter-productive to me to cache pages that are swapped out. If you swap pages in, what is the advantage to first cache them in memory, only to have to than move them to the right ...
5
votes
3answers
1k 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 ...
25
votes
12answers
3k 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 ...