[cgl_discussion] vm strict overcommit question

Zheng, Jeff jeff.zheng at intel.com
Mon Aug 11 18:24:14 PDT 2003


To config if Heuristic or Strict overcommit, just set value of /proc/sys/vm/overcommit_memory:

0: Heuristic overcommit. Default value.
1: No overcommit handle, memory allocation always success
2: Strict overcommit. swap+part of physical memory (configed by /proc/sys/vm/overcommit_ratio).

The issue is if we want swapless strict overcommit, we have to do "swapoff -a".

Thanks
Jeff                        Jeff.Zheng at intel.com
BTW, I speak for myself, not for Intel Corp.


> -----Original Message-----
> From: Fleischer, Julie N 
> Sent: 2003年8月12日 7:00
> To: Zheng, Jeff; cgl_discussion at osdl.org
> Subject: RE: [cgl_discussion] vm strict overcommit question
> 
> 
> > From: Zheng, Jeff 
> > From CGL2.0 requirement, AVF6.1, vm strict overcommit, it 
> > defines two methods for control of virtual memory:
> > + Heuristic overcommit
> > + swapless strict overcommit
> > 
> > The POC reference web site has patchs for both linux-2.4.18 
> > and linux-2.5.26. The patchs define following features:
> > + Heuristic overcommit handling. 
> > + No overcommit handling.
> > + Swapless strict overcommit
> > + Strict overcommit
> > + Paranoid overcommit
> > 
> > But from linux-2.5.28 to newest 2.5 kernel, only three 
> > features survives:
> > + Heuristic overcommit handling. 
> > + No overcommit handling.
> > + Strict overcommit. It is configurable. By applying 
> > parameter to Strict overcommit, it can implement same 
> > functionality as Swapless strict overcommit and Paranoid 
> overcommit. 
> > 
> > My question is: Does AVF6.1, vm strict overcommit, means  
> > "Configurable strict overcommit" + "Heuristic overcommit"?
> 
> Didn't seem like this has been answered yet (although I may 
> have missed it after the F2F)....  My read is that since the 
> requirement is toggleable yes that both swapless strict 
> overcommit and heuristic over-commit just need to be turned 
> on by default, but it's okay if they are configured out later.
> 
> I'll add this data to the POC tracking sheet, though.
> 
> - Julie
> 
> **These views are not necessarily those of my employer.**
> 
> 
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