Messages in this thread | | | Subject | Re: Performance regression in ast drm driver | From | Jean Delvare <> | Date | Mon, 12 Nov 2018 17:41:44 +0100 |
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On Mon, 2018-11-12 at 15:45 +0100, Takashi Iwai wrote: > On Mon, 12 Nov 2018 15:36:07 +0100, > Jean Delvare wrote: > > 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...
Yes, I double checked and can only confirm what I wrote above. However while checking I noticed another strange thing: the contents of pat_memtype_list depend on whether I'm reading the file from an xterm or from the text console (Ctrl+Alt+F2). So I summarize again:
Commit "drm/drivers: add support for using the arch wc mapping API" APPLIED, reading pat_memtype_list from the text console:
uncached-minus @ 0xfafe0000-0xfb000000 uncached-minus @ 0xfb000000-0xfb005000 uncached-minus @ 0xfb000000-0xfb800000 uncached-minus @ 0xfb005000-0xfb584000
Commit "drm/drivers: add support for using the arch wc mapping API" APPLIED, reading pat_memtype_list from an xterm:
uncached-minus @ 0xfafe0000-0xfb000000 uncached-minus @ 0xfb000000-0xfb005000 uncached-minus @ 0xfb000000-0xfb800000
Commit "drm/drivers: add support for using the arch wc mapping API" REVERTED, reading pat_memtype_list from the text console:
uncached-minus @ 0xfafe0000-0xfb000000 uncached-minus @ 0xfb000000-0xfb005000 write-combining @ 0xfb005000-0xfb584000
Commit "drm/drivers: add support for using the arch wc mapping API" REVERTED, reading pat_memtype_list from an xterm:
uncached-minus @ 0xfafe0000-0xfb000000 uncached-minus @ 0xfb000000-0xfb005000
If you don't find it logical, remember that if things were the way they are supposed to be, customers and myself would not be reporting this bug ;-)
-- Jean Delvare SUSE L3 Support
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