slow rx 5600 xt fps

[Alex Deucher]

On Tue, May 19, 2020 at 3:44 PM Javad Karabi <karabijavad at gmail.com> wrote:
>
> just a couple more questions:
>
> - based on what you are aware of, the technical details such as
> "shared buffers go through system memory", and all that, do you see
> any issues that might exist that i might be missing in my setup? i
> cant imagine this being the case because the card works great in
> windows, unless the windows driver does something different?
>

Windows has supported peer to peer DMA for years so it already has a
numbers of optimizations that are only now becoming possible on Linux.

> - as far as kernel config, is there anything in particular which
> _should_ or _should not_ be enabled/disabled?

You'll need the GPU drivers for your devices and dma-buf support.

>
> - does the vendor matter? for instance, this is an xfx card. when it
> comes to different vendors, are there interface changes that might
> make one vendor work better for linux than another? i dont really
> understand the differences in vendors, but i imagine that the vbios
> differs between vendors, and as such, the linux compatibility would
> maybe change?

board vendor shouldn't matter.

>
> - is the pcie bandwidth possible an issue? the pcie_bw file changes
> between values like this:
> 18446683600662707640 18446744071581623085 128
> and sometimes i see this:
> 4096 0 128
> as you can see, the second value seems significantly lower. is that
> possibly an issue? possibly due to aspm?

pcie_bw is not implemented for navi yet so you are just seeing
uninitialized data.  This patch set should clear that up.
https://patchwork.freedesktop.org/patch/366262/

Alex

>
> On Tue, May 19, 2020 at 2:20 PM Javad Karabi <karabijavad at gmail.com> wrote:
> >
> > im using Driver "amdgpu" in my xorg conf
> >
> > how does one verify which gpu is the primary? im assuming my intel
> > card is the primary, since i have not done anything to change that.
> >
> > also, if all shared buffers have to go through system memory, then
> > that means an eGPU amdgpu wont work very well in general right?
> > because going through system memory for the egpu means going over the
> > thunderbolt connection
> >
> > and what are the shared buffers youre referring to? for example, if an
> > application is drawing to a buffer, is that an example of a shared
> > buffer that has to go through system memory? if so, thats fine, right?
> > because the application's memory is in system memory, so that copy
> > wouldnt be an issue.
> >
> > in general, do you think the "copy buffer across system memory might
> > be a hindrance for thunderbolt? im trying to figure out which
> > directions to go to debug and im totally lost, so maybe i can do some
> > testing that direction?
> >
> > and for what its worth, when i turn the display "off" via the gnome
> > display settings, its the same issue as when the laptop lid is closed,
> > so unless the motherboard reads the "closed lid" the same as "display
> > off", then im not sure if its thermal issues.
> >
> > On Tue, May 19, 2020 at 2:14 PM Alex Deucher <alexdeucher at gmail.com> wrote:
> > >
> > > On Tue, May 19, 2020 at 2:59 PM Javad Karabi <karabijavad at gmail.com> wrote:
> > > >
> > > > given this setup:
> > > > laptop -thunderbolt-> razer core x -> xfx rx 5600 xt raw 2 -hdmi-> monitor
> > > > DRI_PRIME=1 glxgears gears gives me ~300fps
> > > >
> > > > given this setup:
> > > > laptop -thunderbolt-> razer core x -> xfx rx 5600 xt raw 2
> > > > laptop -hdmi-> monitor
> > > >
> > > > glx gears gives me ~1800fps
> > > >
> > > > this doesnt make sense to me because i thought that having the monitor
> > > > plugged directly into the card should give best performance.
> > > >
> > >
> > > Do you have displays connected to both GPUs?  If you are using X which
> > > ddx are you using?  xf86-video-modesetting or xf86-video-amdgpu?
> > > IIRC, xf86-video-amdgpu has some optimizations for prime which are not
> > > yet in xf86-video-modesetting.  Which GPU is set up as the primary?
> > > Note that the GPU which does the rendering is not necessarily the one
> > > that the displays are attached to.  The render GPU renders to it's
> > > render buffer and then that data may end up being copied other GPUs
> > > for display.  Also, at this point, all shared buffers have to go
> > > through system memory (this will be changing eventually now that we
> > > support device memory via dma-buf), so there is often an extra copy
> > > involved.
> > >
> > > > theres another really weird issue...
> > > >
> > > > given setup 1, where the monitor is plugged in to the card:
> > > > when i close the laptop lid, my monitor is "active" and whatnot, and i
> > > > can "use it" in a sense
> > > >
> > > > however, heres the weirdness:
> > > > the mouse cursor will move along the monitor perfectly smooth and
> > > > fine, but all the other updates to the screen are delayed by about 2
> > > > or 3 seconds.
> > > > that is to say, its as if the laptop is doing everything (e.g. if i
> > > > open a terminal, the terminal will open, but it will take 2 seconds
> > > > for me to see it)
> > > >
> > > > its almost as if all the frames and everything are being drawn, and
> > > > the laptop is running fine and everything, but i simply just dont get
> > > > to see it on the monitor, except for one time every 2 seconds.
> > > >
> > > > its hard to articulate, because its so bizarre. its not like, a "low
> > > > fps" per se, because the cursor is totally smooth. but its that
> > > > _everything else_ is only updated once every couple seconds.
> > >
> > > This might also be related to which GPU is the primary.  It still may
> > > be the integrated GPU since that is what is attached to the laptop
> > > panel.  Also the platform and some drivers may do certain things when
> > > the lid is closed.  E.g., for thermal reasons, the integrated GPU or
> > > CPU may have a more limited TDP because the laptop cannot cool as
> > > efficiently.
> > >
> > > Alex