Re: [vserver] Unification and memory usage

From: Roderick A. Anderson <>
Date: Tue 03 May 2011 - 00:09:29 BST
Message-ID: <>

Gordan Bobic wrote:
> On 02/05/2011 23:14, Roderick A. Anderson wrote:
>> I've got myself confused again. Could someone confirm or deny how
>> unification affects memory usage.
>> I was under the impression that if a unified (hard linked) "program" was
>> started by one guest the code for it went into the text area of memory
>> and any needed data area was allocated from the heap. Then when another
>> guest started the same program kernel-magic happened and basically the
>> same code was used but a new chunk of heap was allocated/used for its
>> data.
>> I'd like to make a simplified drawing of how the Linux-Vserver way with
>> unification saves memory. Have I got it all wrong?
> I believe the memory unification only applies to the shared memory
> mmap-ed from hard-linked DLLs. If you have the same glibc unified across
> all your guests, only one instance of it will be in memory. Unified
> executables won't save you memory in this way.

Thanks. This make more sense too.

> What you will gain on all unified files, however, is caching efficiency,
> as you won't end up with multiple copies of the same file being cached
> separately.

Again thanks. Helps a lot.

I'll have to revise my graphic plans but they hadn't gone very far
anyway once I realized I was confused. :-)


Received on Tue May 3 00:09:42 2011
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