Re: i915.ko WC writes are slow after ea8596bb2d8d379

From: Chris Wilson
Date: Thu Oct 09 2014 - 11:15:48 EST

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On Thu, Oct 09, 2014 at 09:46:37AM -0500, Chuck Ebbert wrote:
> Well they're all the same.
>
> Hmm, x86info is not dumping all the variable MTRRs. You have 10, but
> it only prints the first 8. I don't know if it will show anything
> different, but can you try fixing it with this patch?

Source (https://github.com/dankamongmen/x86info) was slightly different,
but I followed the drift.

tldr: 8,9 appear to be identical on all cpus as well.

$ sudo ./x86info --mtrr --all-cpus
x86info v1.31pre
Found 4 CPUs.
CPU #1:
Extended Family: 0 Extended Model: 2 Family: 6 Model: 42 Stepping: 7
Type: 0 (Original OEM)
CPU Model (x86info's best guess): Core i7 (SandyBridge)
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a wc:1 fix:1 vcnt:10
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase:0x000000 type: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase:0x080000 type: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase:0x08e000 type: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask:0xffe000 valid:1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase:0x08d000 type: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase:0x100000 type: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase:0x170000 type: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase:0x16f000 type: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase:0x16e800 type: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask:0xfff800 valid:1)
MTRRphysBase8 (0x210): 0x000000016e600000 (physbase:0x16e600 type: 0x00 (uncacheable))
MTRRphysMask8 (0x211): 0x0000000fffe00800 (physmask:0xfffe00 valid:1)
MTRRphysBase9 (0x212): 0x0000000000000000 (physbase:0x000000 type: 0x00 (uncacheable))
MTRRphysMask9 (0x213): 0x0000000000000000 (physmask:0x000000 valid:0)
MTRRfix64K_00000 (0x250): 0x0606060606060606
MTRRfix16K_80000 (0x258): 0x0606060606060606
MTRRfix16K_A0000 (0x259): 0x0000000000000000
MTRRfix4K_C8000 (0x269): 0x0505050505050505
MTRRfix4K_D0000 0x26a: 0x0000000000000000
MTRRfix4K_D8000 0x26b: 0x0000000000000000
MTRRfix4K_E0000 0x26c: 0x0000000000000000
MTRRfix4K_E8000 0x26d: 0x0505050505050505
MTRRfix4K_F0000 0x26e: 0x0505050505050505
MTRRfix4K_F8000 0x26f: 0x0505050505050505
MTRRdefType (0x2ff): 0x0000000000000c00 (fixed-range flag:1 enable flag:1 default type:0x00 (uncacheable))

--------------------------------------------------------------------------
CPU #2:
Extended Family: 0 Extended Model: 2 Family: 6 Model: 42 Stepping: 7
Type: 0 (Original OEM)
CPU Model (x86info's best guess): Core i7 (SandyBridge)
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a wc:1 fix:1 vcnt:10
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase:0x000000 type: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase:0x080000 type: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase:0x08e000 type: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask:0xffe000 valid:1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase:0x08d000 type: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase:0x100000 type: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase:0x170000 type: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase:0x16f000 type: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase:0x16e800 type: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask:0xfff800 valid:1)
MTRRphysBase8 (0x210): 0x000000016e600000 (physbase:0x16e600 type: 0x00 (uncacheable))
MTRRphysMask8 (0x211): 0x0000000fffe00800 (physmask:0xfffe00 valid:1)
MTRRphysBase9 (0x212): 0x0000000000000000 (physbase:0x000000 type: 0x00 (uncacheable))
MTRRphysMask9 (0x213): 0x0000000000000000 (physmask:0x000000 valid:0)
MTRRfix64K_00000 (0x250): 0x0606060606060606
MTRRfix16K_80000 (0x258): 0x0606060606060606
MTRRfix16K_A0000 (0x259): 0x0000000000000000
MTRRfix4K_C8000 (0x269): 0x0505050505050505
MTRRfix4K_D0000 0x26a: 0x0000000000000000
MTRRfix4K_D8000 0x26b: 0x0000000000000000
MTRRfix4K_E0000 0x26c: 0x0000000000000000
MTRRfix4K_E8000 0x26d: 0x0505050505050505
MTRRfix4K_F0000 0x26e: 0x0505050505050505
MTRRfix4K_F8000 0x26f: 0x0505050505050505
MTRRdefType (0x2ff): 0x0000000000000c00 (fixed-range flag:1 enable flag:1 default type:0x00 (uncacheable))

--------------------------------------------------------------------------
CPU #3:
Extended Family: 0 Extended Model: 2 Family: 6 Model: 42 Stepping: 7
Type: 0 (Original OEM)
CPU Model (x86info's best guess): Core i7 (SandyBridge)
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a wc:1 fix:1 vcnt:10
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase:0x000000 type: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase:0x080000 type: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase:0x08e000 type: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask:0xffe000 valid:1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase:0x08d000 type: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase:0x100000 type: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase:0x170000 type: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase:0x16f000 type: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase:0x16e800 type: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask:0xfff800 valid:1)
MTRRphysBase8 (0x210): 0x000000016e600000 (physbase:0x16e600 type: 0x00 (uncacheable))
MTRRphysMask8 (0x211): 0x0000000fffe00800 (physmask:0xfffe00 valid:1)
MTRRphysBase9 (0x212): 0x0000000000000000 (physbase:0x000000 type: 0x00 (uncacheable))
MTRRphysMask9 (0x213): 0x0000000000000000 (physmask:0x000000 valid:0)
MTRRfix64K_00000 (0x250): 0x0606060606060606
MTRRfix16K_80000 (0x258): 0x0606060606060606
MTRRfix16K_A0000 (0x259): 0x0000000000000000
MTRRfix4K_C8000 (0x269): 0x0505050505050505
MTRRfix4K_D0000 0x26a: 0x0000000000000000
MTRRfix4K_D8000 0x26b: 0x0000000000000000
MTRRfix4K_E0000 0x26c: 0x0000000000000000
MTRRfix4K_E8000 0x26d: 0x0505050505050505
MTRRfix4K_F0000 0x26e: 0x0505050505050505
MTRRfix4K_F8000 0x26f: 0x0505050505050505
MTRRdefType (0x2ff): 0x0000000000000c00 (fixed-range flag:1 enable flag:1 default type:0x00 (uncacheable))

--------------------------------------------------------------------------
CPU #4:
Extended Family: 0 Extended Model: 2 Family: 6 Model: 42 Stepping: 7
Type: 0 (Original OEM)
CPU Model (x86info's best guess): Core i7 (SandyBridge)
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a wc:1 fix:1 vcnt:10
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase:0x000000 type: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase:0x080000 type: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase:0x08e000 type: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask:0xffe000 valid:1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase:0x08d000 type: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase:0x100000 type: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask:0xf80000 valid:1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase:0x170000 type: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask:0xff0000 valid:1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase:0x16f000 type: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask:0xfff000 valid:1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase:0x16e800 type: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask:0xfff800 valid:1)
MTRRphysBase8 (0x210): 0x000000016e600000 (physbase:0x16e600 type: 0x00 (uncacheable))
MTRRphysMask8 (0x211): 0x0000000fffe00800 (physmask:0xfffe00 valid:1)
MTRRphysBase9 (0x212): 0x0000000000000000 (physbase:0x000000 type: 0x00 (uncacheable))
MTRRphysMask9 (0x213): 0x0000000000000000 (physmask:0x000000 valid:0)
MTRRfix64K_00000 (0x250): 0x0606060606060606
MTRRfix16K_80000 (0x258): 0x0606060606060606
MTRRfix16K_A0000 (0x259): 0x0000000000000000
MTRRfix4K_C8000 (0x269): 0x0505050505050505
MTRRfix4K_D0000 0x26a: 0x0000000000000000
MTRRfix4K_D8000 0x26b: 0x0000000000000000
MTRRfix4K_E0000 0x26c: 0x0000000000000000
MTRRfix4K_E8000 0x26d: 0x0505050505050505
MTRRfix4K_F0000 0x26e: 0x0505050505050505
MTRRfix4K_F8000 0x26f: 0x0505050505050505
MTRRdefType (0x2ff): 0x0000000000000c00 (fixed-range flag:1 enable flag:1 default type:0x00 (uncacheable))

--------------------------------------------------------------------------
Total processor threads: 4
This system has 1 dual-core processor with hyper-threading (2 threads per core) running at an estimated 3.30GHz

--
Chris Wilson, Intel Open Source Technology Centre
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