Re: i915.ko WC writes are slow after ea8596bb2d8d379

From: Chris Wilson
Date: Thu Oct 09 2014 - 09:01:45 EST


On Thu, Oct 09, 2014 at 07:44:16AM -0500, Chuck Ebbert wrote:
> Could you try installing x86info and running "x86info --mtrr
> --all-cpus" while running the broken kernel?

# /opt/xorg/src/intel-gpu-tools/tests/gem_gtt_speed
IGT-Version: 1.8-g32a0308 (x86_64) (Linux: 3.17.0+ x86_64)
Time to read 16k through a GTT map: 318.643µs
Time to write 16k through a GTT map: 203.103µs
Time to clear 16k through a GTT map: 53.098µs
Time to clear 16k through a cached GTT map: 49.925µs

(i.e. bad kernel)

# x86info --mtrr --all-cpus
x86info v1.30. Dave Jones 2001-2011
Feedback to <davej@xxxxxxxxxx>.

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): Unknown model.
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a (smrr flag: 0x1, wc flag: 0x1, fix flag: 0x1, vcnt field: 0x0a (10))
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase field:0x000000 type field: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase field:0x080000 type field: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase field:0x08e000 type field: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask field:0xffe000 valid flag: 1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase field:0x08d000 type field: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase field:0x100000 type field: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase field:0x170000 type field: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase field:0x16f000 type field: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase field:0x16e800 type field: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask field:0xfff800 valid flag: 1)
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: 0x1, mtrr flag: 0x1, type field: 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): Unknown model.
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a (smrr flag: 0x1, wc flag: 0x1, fix flag: 0x1, vcnt field: 0x0a (10))
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase field:0x000000 type field: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase field:0x080000 type field: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase field:0x08e000 type field: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask field:0xffe000 valid flag: 1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase field:0x08d000 type field: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase field:0x100000 type field: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase field:0x170000 type field: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase field:0x16f000 type field: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase field:0x16e800 type field: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask field:0xfff800 valid flag: 1)
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: 0x1, mtrr flag: 0x1, type field: 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): Unknown model.
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a (smrr flag: 0x1, wc flag: 0x1, fix flag: 0x1, vcnt field: 0x0a (10))
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase field:0x000000 type field: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase field:0x080000 type field: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase field:0x08e000 type field: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask field:0xffe000 valid flag: 1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase field:0x08d000 type field: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase field:0x100000 type field: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase field:0x170000 type field: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase field:0x16f000 type field: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase field:0x16e800 type field: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask field:0xfff800 valid flag: 1)
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: 0x1, mtrr flag: 0x1, type field: 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): Unknown model.
Processor name string (BIOS programmed): Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz

MTRR registers:
MTRRcap (0xfe): 0x0000000000000d0a (smrr flag: 0x1, wc flag: 0x1, fix flag: 0x1, vcnt field: 0x0a (10))
MTRRphysBase0 (0x200): 0x0000000000000006 (physbase field:0x000000 type field: 0x06 (write-back))
MTRRphysMask0 (0x201): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase1 (0x202): 0x0000000080000006 (physbase field:0x080000 type field: 0x06 (write-back))
MTRRphysMask1 (0x203): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase2 (0x204): 0x000000008e000000 (physbase field:0x08e000 type field: 0x00 (uncacheable))
MTRRphysMask2 (0x205): 0x0000000ffe000800 (physmask field:0xffe000 valid flag: 1)
MTRRphysBase3 (0x206): 0x000000008d000000 (physbase field:0x08d000 type field: 0x00 (uncacheable))
MTRRphysMask3 (0x207): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase4 (0x208): 0x0000000100000006 (physbase field:0x100000 type field: 0x06 (write-back))
MTRRphysMask4 (0x209): 0x0000000f80000800 (physmask field:0xf80000 valid flag: 1)
MTRRphysBase5 (0x20a): 0x0000000170000000 (physbase field:0x170000 type field: 0x00 (uncacheable))
MTRRphysMask5 (0x20b): 0x0000000ff0000800 (physmask field:0xff0000 valid flag: 1)
MTRRphysBase6 (0x20c): 0x000000016f000000 (physbase field:0x16f000 type field: 0x00 (uncacheable))
MTRRphysMask6 (0x20d): 0x0000000fff000800 (physmask field:0xfff000 valid flag: 1)
MTRRphysBase7 (0x20e): 0x000000016e800000 (physbase field:0x16e800 type field: 0x00 (uncacheable))
MTRRphysMask7 (0x20f): 0x0000000fff800800 (physmask field:0xfff800 valid flag: 1)
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: 0x1, mtrr flag: 0x1, type field: 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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