Re: VM tuning through fault trace gathering [with actual code]

[Marcelo Tosatti <marcelo@conectiva.com.br>]

On Wed, 27 Jun 2001, Scott F.Kaplan wrote:

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> On Wednesday 27 June 2001 06:09 am, Marcelo Tosatti wrote:
> > On 26 Jun 2001, John Fremlin wrote:
> > > Marcelo Tosatti <marcelo@conectiva.com.br> writes:
> > > > ####################################################################
> > > > Event     	          Time                   PID     Length Description
> > > > ####################################################################
> > > >
> > > > Trap entry              991,299,585,597,016     678     12      TRAP:
> > > > page fault; EIP : 0x40067785
> > >
> > > That looks like just the generic interrupt handling. It does not do
> > > what I want to do, i.e. record some more info about the fault saying
> > > where it comes from.
> >
> > You can create custom events with LTT and then you can get them from a
> > "big buffer" to userlevel later, then.
> 
> I guess that i have a different concern with this existing utility.  It seems 
> that it will report page faults (minor or major) for the normal VM system 
> configuration.  What if we want it to record all (or nearly) all page 
> references, even ones to pages that *normally* wouldn't cause any kind of 
> interrupt?  That ability seems new and unique to John's utility.
> 
> (I know, I need to read the LLT manual, as it may be able to do exactly what 
> I'm describing.  However, I don't think that's the case.)

You are right here. 

But anyway, I think John can do what he wants without writting a whole
new tracing facility. 

IMHO. 

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