RE: [GD-General] Assistance with VTune results required

[Tom F. <to...@mu...>]

More wild guesswork - READ_PORT_ULONG reads a ULONG from a hardware
register? This is a common part of waiting until a blit has completed on the
hardware. This is done so that rendering in a windows doesn't buffer up
hundreds of frames - the driver waits until the blit used by Present()
actually finishes rendering before submitting any more data.

When you go fullscreen, you're using a buffer flip instead, which often uses
a different throttling mechanism.

No idea what HalRequestlpi does. Best ask Richard Huddy - he's the nVidia
driver expert.


Tom Forsyth - purely hypothetical Muckyfoot bloke.

This email is the product of your deranged imagination,
and does not in any way imply existence of the author.

> -----Original Message-----
> From: Barstow Jason [mailto:JBa...@uk...]
> Sent: 06 March 2002 15:50
> To: gam...@li...
> Subject: RE: [GD-General] Assistance with VTune results required
> 
> 
> > > hall.dll			35%
> > > 
> > > That 35% in hall.dll breaks down to
> > > 	READ_PORT_ULONG
> > > and
> > > 	HalRequestlpi
> > > (among some others)
> > 
> > A wild guess: "hall" ~= "hardware abstraction layer <something>"
> > 
> > Another guess: the time is spent waiting for the graphics card to
> > complete some operations.  I.e. your CPU has more graphics commands
> > for your GPU, but has to wait for the GPU input queue to have some
> > room before it can write the new commands.  Meanwhile the 
> GPU is busy
> > filling pixels.
> > 
> > Try rendering to a smaller window to see if the time proportions
> > change.
> 
> Sorry, I made a typo; it is indeed hal.dll (the kernal 
> hardware abstraction
> layer)
> I ran the initial test @ 400 x 300 x 16bit windowed.
> 
> I've subsequently disabled rendering altogether (the 
> device->Present still
> operative)
> and sound and dplay and dinput, and the spike is still there.
> 
> However, switching to fullscreen and the READ_PORT_ULONG disappears.
> (HalRequestlpi is still there.)
> 
> 
> 
> 
> 
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