There is a bigger issue. Linux was written assuming dedicated resource and slow disks. It does everything it can to consume available storage and avoid disk I/O. Under VM, we need Linux to understand "shared resource". The real issue is how much code should put into the kernal to support VM - Ingo can answer to that....
What is needed is control over the buffer and cache size that linux uses. Turning them off is probably undesirable, but controlling their size would be very desirable. Currently as Mark said, the only way to control sizes of buffer/cache is to reduce the size of the virtual machine. Then create a virtual disk and use for swap. Linux will then have additional storage when needed, but will not use that storage for buffer/cache - this is desirable. But today, having 100 linux servers share the same read/only disk, and all 100 cache the same disk is undesirable when MDC could do it so well for all of them. Even having control over which disks linux caches would be desirable, but not currently possible (I think...) >From: Werner Puschitz <[EMAIL PROTECTED]> > >Does anyone know if there are any plans to address it in the near >future? Isn't this a big drawback for Linux on zSeries? > > >On Thu, 25 Apr 2002, Barton Robinson wrote: > >> The author is correct. This has NOT been addressed for Linux >> on zSeries. >> >> >From: Werner Puschitz <[EMAIL PROTECTED]> >> > >> >Is the author right on this: >> > >> >http://www.linuxworld.com/site-stories/2002/0416.mainframelinux-p7.html >> >"Linux memory management assumes control of a machine and so grabs up >> >free memory for use in I/O buffering. Having multiple Linux instances do >> >this to independently buffer I/O to the same files resident on a shared >> >mini-disk not only wastes memory, but dramatically increases the paging >> >effort." >> > >> >Or has this already been addressed for Linux on zSeries? >> > >> >Thanks >> >Werner "If you can't measure it, I'm Just NOT interested!"(tm) /************************************************************/ Barton Robinson - CBW Internet: [EMAIL PROTECTED] Velocity Software, Inc Mailing Address: 196-D Castro Street P.O. Box 390640 Mountain View, CA 94041 Mountain View, CA 94039-0640 VM Performance Hotline: 650-964-8867 Fax: 650-964-9012 Web Page: WWW.VELOCITY-SOFTWARE.COM /************************************************************/
