On Mon, 12 Nov 2018 15:36:07 +0100, Jean Delvare wrote: > > Hi David, > > On Fri, 2018-11-09 at 10:04 +1000, David Airlie wrote: > > On Thu, Nov 8, 2018 at 10:05 PM Jean Delvare <jdelvare@xxxxxxx> wrote: > > > > > > On Thu, 1 Nov 2018 16:27:07 +0100, Jean Delvare wrote: > > > > Hi David, > > > > > > > > The following commit: > > > > > > > > commit 7cf321d118a825c1541b43ca45294126fd474efa > > > > Author: Dave Airlie > > > > Date: Mon Oct 24 15:37:48 2016 +1000 > > > > > > > > drm/drivers: add support for using the arch wc mapping API. > > > > > > > > is causing a huge performance regression for the ast drm driver. In a > > > > text console, if I call "cat" on a large text file, it takes almost > > > > twice as much time to be displayed and scrolled completely. > > > > > > > > Can you please check that the ast driver portion of that commit is both > > > > correct and complete? > > > > > > And in the meantime, what bad will happen if we just revert the ast > > > portion of that commit? > > > > This seems likely to be a hw problem with PCI writes to the AST "GPU", > > since it's just some sort of RAM + ARM on the end of a PCIE bus, we've > > definitely seen possible issues in the past with write combining > > around some of the mga GPUs with some CPUs. > > Takashi asked me to compare the contents of > /sys/kernel/debug/x86/pat_memtype_list before and after the commit > above. Before the commit, we have: > > uncached-minus @ 0xfafe0000-0xfb000000 > uncached-minus @ 0xfb000000-0xfb005000 > write-combining @ 0xfb005000-0xfb584000 > > After the commit, we have: > > uncached-minus @ 0xfafe0000-0xfb000000 > uncached-minus @ 0xfb000000-0xfb005000 > uncached-minus @ 0xfb000000-0xfb800000 > uncached-minus @ 0xfb005000-0xfb584000 Just to be sure: could you double-check whether you're checking the right order (i.e. not checking against the revert)? The change above looks illogical from what I can see from the commit... thanks, Takashi > > The corresponding lines in /proc/iomem are: > > f0000000-fed8ffff : PCI Bus 0000:00 > faf00000-fb7fffff : PCI Bus 0000:01 > fafe0000-faffffff : 0000:01:01.0 > fb000000-fb7fffff : 0000:01:01.0 > > Does it help? Is the change of type expected? Is it not a problem that > one of the ranges is overlapping with 2 other ranges? > > -- > Jean Delvare > SUSE L3 Support > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
