The intention is that you shouldn't be touching the default settings
(e.g., in PhysicalMemory.py) at all; you should be setting them
yourself in your simulation script (e.g., configs/example/se.py, or
whatever you're using). For example, something like this:
system.physmem.latency = '1ms'
The config.ini file that gets generated when you run will confirm
whether or not the latency parameter is really getting updated.
If the parameter is getting updated and your timing still isn't
changing, you can use gdb or traceflags to see what's really
happening, e.g., look for a PhysicalMemory access and see if it's
really taking longer.
Steve
On Nov 26, 2007 2:25 PM, abc def <[EMAIL PROTECTED]> wrote:
> Actually my question is very simple:
>
> I want to change L1 hit latency:memory access latency
> from default settings. Which file shall i change?
>
> I am running timing simple cpu with all default
> configurations.
>
> I tried to modify latency option in PhysicalMemory.py
> but looks like it is not changing the execution time
> of the program.
>
> I measure execution time as difference of cpu tick
> value between whenever a program starts and when it
> ends ( i capture start and end of the program by a
> different flag).
>
> --- Ali Saidi <[EMAIL PROTECTED]> escribió:
>
>
> > Please provide as much information about what you're
> > trying to do is
> > as possible, it's really the only way we can help
> > you and prevents
> > large exchanges of e-mails without any resolution.
> >
> > 1. What did you set the parameters to be?
> > 2. Have you tried using a the Physical Memory
> > instead of the DRAM one?
> > 3. What CPU model are you using? If you're using an
> > atomic cpu and
> > haven't change any parameters on it, the access
> > latency it gets back
> > from memory doesn't matter
> >
> > Ali
> >
> > On Nov 26, 2007, at 9:43 AM, abc def wrote:
> >
> > > Can you please tell me where should i change to
> > get
> > > the effect? I changed in
> > > src/python/m5/objects/PhysicalMemory.py as
> > follows:
> > > "cpu_ratio = Param.Int(10,"ratio between CPU speed
> > and
> > > memory bus speed") "
> > >
> > > Also changed "latency = Param.Latency('1ms',
> > "latency
> > > of an access")" but execution time is remaining
> > > exactly same (by execution time i am referring to
> > tick
> > > value difference between program start and end)
> > >
> > > --- Steve Reinhardt <[EMAIL PROTECTED]> escribió:
> > >
> > >> Have you looked at the latency settings for the
> > bus
> > >> and main memory?
> > >> The defaults for these are unreasonably low. If
> > you
> > >> want realistic
> > >> results you'll have to modify these parameters to
> > >> whatever you believe
> > >> to be realistic values.
> > >>
> > >> Steve
> > >>
> > >> On Nov 24, 2007 11:31 AM, abc def
> > >> <[EMAIL PROTECTED]> wrote:
> > >>>> From trace files it seems that cache hit
> > latency
> > >> is
> > >>> around 1000 ticks to 2000 ticks, but if it
> > misses
> > >> then
> > >>> the latency is ~6000 cycles but not more. Now in
> > >> the
> > >>> simulation there is no L2 so,how come second
> > >> latency
> > >>> which is the memory access latency is so close
> > of
> > >> L1
> > >>> access latency?
> > >>>
> > >>>
> > >>>
> > >>> ______________________________________________
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> > >
> > >
> > >
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>
>
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