Re: Kernel and ADM hardware roulette ( was AMD graphics performance regression in 4.15 and later )

[Christian KÃnig]

Hi Christopher,

Am 07.06.2018 um 18:24 schrieb Gabriel C:
> > [SNIP]
> > Ok done.. bisect points to:
> >
> > b468620f2a1dfdcfddfd6fa54367b8bcc1b51248 is the first bad commit
> > commit b468620f2a1dfdcfddfd6fa54367b8bcc1b51248
> > Author: Christoph Hellwig <hch@xxxxxx>
> > Date:   Mon Mar 19 11:38:19 2018 +0100
> >
> >     iommu/amd_iommu: Use CONFIG_DMA_DIRECT_OPS=y and dma_direct_{alloc,free}()
> >
> >     This cleans up the code a lot by removing duplicate logic.
> >
> >     Tested-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> >     Tested-by: Joerg Roedel <jroedel@xxxxxxx>
> >     Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> >     Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> >     Acked-by: Joerg Roedel <jroedel@xxxxxxx>
> >     Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
> >     Cc: Joerg Roedel <joro@xxxxxxxxxx>
> >     Cc: Jon Mason <jdmason@xxxxxxxx>
> >     Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> >     Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> >     Cc: Muli Ben-Yehuda <mulix@xxxxxxxxx>
> >     Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> >     Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> >     Link: http://lkml.kernel.org/r/20180319103826.12853-8-hch@xxxxxx
> >     Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> >
> >
> > I'll try to revert this once I'm home.
> I can confirm reverting b468620f2a1dfdcfddfd6fa54367b8bcc1b51248
> fixes that issue for me.

any idea what could cause that? Basically this patch breaks radeon when 
SME is enabled.

> The GPU is working fine with SME enabled.
>
> Now with working GPU :) I can also confirm performance is back to normal
> without doing any other workarounds.
>
> The only app still acting up a bit is Firefox , just minor frame drops,
> but nothing to bad.  ( probably an Firefox bug too )
>
> crhomium/chrome is fine .. even with 10 tabs open , each one playing
> an video on youtube no glitches at all.
>
> Desktop is also fine now,  could not find anything wrong.

Thanks for testing,
Christian.

> BR