So how does one determine the size, in memory, of the uncompressed kernel image? That would give me more sense of the savings of doing this. I feel the savings will be insignificant at the scale we are currently at, but hard numbers are helpful.
Linux on 390 Port <LINUX-390@VM.MARIST.EDU> wrote on 02/23/2007 09:45:30 AM: > On 2/23/07, James Melin <[EMAIL PROTECTED]> wrote: > > > Sadly, no. I am not joking. I was told to remove it, so I did. > Under protest. Had it working perfectly. I think it's time to re- > visit this, however. > > Yes, you should. Some VM folks have old thumbs whose rules don't fit > current workload. > > > What we're being directed to do here at the moment is do shared > kernel. I'm running a MAXIMUM of 11 images right now. Three of them > on the Test VM > > LPAR. So what is the benefit? I have two 'test' systems on the > prod VM. One is my cloning/update server Two prod websphere, one prod DB2 > > Connect/CVS/Bugzilla/MySQL instance and 2 QA Websphere instances. > In that environment I am going to need at least two shared kernel > images. Probably > > three. So that will buy me the memory footprint of maybe five > images at maximum. > > There are measurable advantages in sharing the kernel when you are > short on memory. Think about the paging handshake between Linux and VM > that will let Linux run another process while VM is resolving the page > fault. But a page fault in the kernel stops the entire virtual > machine. With the kernel in NSS those pages are less likely to get > paged out. That's also part of the motivation for shared libraries in > XIP. It helps to let VM treat one page different from the other. > > Whether advantages outweigh the cost for your installation depends on > many things. Not all pure technical. > > Rob > -- > Rob van der Heij > Velocity Software, Inc > http://velocitysoftware.com/ > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
