On Thu, Nov 4, 2010 at 5:58 PM, Bryan O'Neal < Bryan.ONeal@theonealandassociates.com> wrote: > Setting swapiness is how I can deal with a recurrence but it will not > flush current swap. And I can not shut down any process to perform > swap off. :( > > On 11/4/10, Eric Shubert wrote: > > On 11/04/2010 03:26 PM, Bryan O'Neal wrote: > >> Please no debates on why I need to clear swap... > >> > >> If I have a box with 20% free ram and 5% free swap but no paging > >> activity - how do I force linux to release the allocated swap? I have > >> ~ 2x as much allocated swap as free memory so simply turning swap off > >> seems like a bad idea. > >> > >> Thanks > >> > > > > To minimize swap use, put > > vm.swappiness = 0 > > in /etc/sysctl.conf file. You can also change it on the fly in the > > /proc/sys/vm/swappiness. > > See http://unixfoo.blogspot.com/2007/11/linux-performance-tuning.html > > > > AFA purging the swap file is concerned, I only know to stop and start it > > again: > > # swapoff -a && swapon -a > > You might not run into trouble doing this, as there's probably a good > > deal of (filesystem) cached ram being used that the kernel will give up > > if it's needed for running processes. Do the math though to be sure you > > won't run out. Either that or stop some less important processes while > > you do it. > > > > -- > > -Eric 'shubes' > > > > I would leave the current swap, in case you start thrashing, however, you requested we not debate, here's the howto: Type following command to create 512MB swap file (1024 * 512MB = 524288 block size): # dd if=/dev/zero of=/swapfile1 bs=1024 count=524288 c) Set up a Linux swap area: # mkswap /swapfile1 d) Activate /swapfile1 swap space immediately: # swapon /swapfile1 e) To activate /swapfile1 after Linux system reboot, add entry to /etc/fstab file. Open this file using text editor such as vi: # vi /etc/fstab Append following line: /swapfile1 swap swap defaults 0 0 And comment out the old swapfile. You can swapoff the old file also, but I would, in a production machine test the full swap utilization after changes through a reboot. -- Skype: 6022393392 ATT: 5037544452 GV: 6236883392 http://www.it-clowns.com Politicians should read science fiction, not westerns and detective stories. -Arthur C. Clark I am free because I know that I alone am morally responsible for everything I do. -Heinlein