[Mesa-dev] [PATCH 00/12] Do better for flrp on platforms that lack flrp instruction, take 2

[Ian Romanick]

Bump.

On 08/24/2018 10:52 PM, Ian Romanick wrote:
> This series replaces my previous series
> (https://patchwork.freedesktop.org/series/48138/) that did similar
> things.  Rather than trying to do everything with only local information
> in nir_opt_algebraic, this series adds a new optimization pass.  This
> new pass looks at how various parameters of a nir_op_flrp are used in
> other nir_op_flrp instructions to make better choices.
> 
> You can compare the results across this whole series, below, with the
> similar results in the previous series.  At least for Intel GPUs, this
> series does quite a bit better.  There are a couple extra loops and a
> couple lost SIMD16 shaders on Iron Lake, but the trade off is an extra
> 35 (+32 overall) SIMD16 shaders on Iron Lake and an 38 SIMD16 shaders on
> GM45.
> 
> It also shouldn't break the whole universe for non-Intel GPUs. :)
> Neither of the tested Intel GPUs have an FMA instruction, so I don't
> know how this series will affect GPUs that lack LRP but have FMA.  I did
> some testing on Ice Lake, which lacks LRP but has FMA, and the results
> were mixed but generally positive.  There is some driver support missing
> for the FMA on Ice Lake, so those results are not likely to be
> representative of the final result.
> 
> I have another series waiting to go out that improves LRP and FMA
> generation for all of the Intel platforms that support LRP and FMA.
> That series caused a bunch of regressions on the non-LRP platforms, so
> this series needs to land first.
> 
> This series, along with a few patches that didn't pan out, is available
> at:
> 
>     https://cgit.freedesktop.org/~idr/mesa/log/?h=lower-flrp
> 
> Iron Lake
> total instructions in shared programs: 7774533 -> 7676404 (-1.26%)
> instructions in affected programs: 4436203 -> 4338074 (-2.21%)
> helped: 19242
> HURT: 924
> helped stats (abs) min: 1 max: 155 x̄: 5.16 x̃: 3
> helped stats (rel) min: 0.11% max: 86.96% x̄: 2.85% x̃: 1.89%
> HURT stats (abs)   min: 1 max: 8 x̄: 1.29 x̃: 1
> HURT stats (rel)   min: 0.08% max: 6.52% x̄: 1.22% x̃: 1.01%
> 95% mean confidence interval for instructions value: -4.95 -4.79
> 95% mean confidence interval for instructions %-change: -2.71% -2.61%
> Instructions are helped.
> 
> total cycles in shared programs: 177757572 -> 177292132 (-0.26%)
> cycles in affected programs: 100318508 -> 99853068 (-0.46%)
> helped: 18971
> HURT: 1407
> helped stats (abs) min: 2 max: 930 x̄: 25.18 x̃: 12
> helped stats (rel) min: <.01% max: 94.58% x̄: 1.24% x̃: 0.55%
> HURT stats (abs)   min: 2 max: 98 x̄: 8.71 x̃: 6
> HURT stats (rel)   min: <.01% max: 4.11% x̄: 0.33% x̃: 0.14%
> 95% mean confidence interval for cycles value: -23.31 -22.37
> 95% mean confidence interval for cycles %-change: -1.16% -1.09%
> Cycles are helped.
> 
> total loops in shared programs: 850 -> 854 (0.47%)
> loops in affected programs: 0 -> 4
> helped: 0
> HURT: 4
> HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
> HURT stats (rel)   min: 0.00% max: 0.00% x̄: 0.00% x̃: 0.00%
> 95% mean confidence interval for loops value: 1.00 1.00
> 95% mean confidence interval for loops %-change: 0.00% 0.00%
> Loops are HURT.
> 
> LOST:   3
> GAINED: 52
> 
> GM45
> total instructions in shared programs: 4766579 -> 4715273 (-1.08%)
> instructions in affected programs: 2372653 -> 2321347 (-2.16%)
> helped: 9929
> HURT: 467
> helped stats (abs) min: 1 max: 155 x̄: 5.23 x̃: 3
> helped stats (rel) min: 0.11% max: 86.96% x̄: 2.78% x̃: 1.86%
> HURT stats (abs)   min: 1 max: 8 x̄: 1.28 x̃: 1
> HURT stats (rel)   min: 0.08% max: 6.25% x̄: 1.19% x̃: 1.00%
> 95% mean confidence interval for instructions value: -5.05 -4.82
> 95% mean confidence interval for instructions %-change: -2.67% -2.54%
> Instructions are helped.
> 
> total cycles in shared programs: 121450872 -> 121161308 (-0.24%)
> cycles in affected programs: 61826744 -> 61537180 (-0.47%)
> helped: 9846
> HURT: 759
> helped stats (abs) min: 2 max: 930 x̄: 30.12 x̃: 12
> helped stats (rel) min: <.01% max: 93.33% x̄: 1.30% x̃: 0.58%
> HURT stats (abs)   min: 2 max: 98 x̄: 9.27 x̃: 6
> HURT stats (rel)   min: <.01% max: 4.11% x̄: 0.33% x̃: 0.13%
> 95% mean confidence interval for cycles value: -28.06 -26.55
> 95% mean confidence interval for cycles %-change: -1.23% -1.14%
> Cycles are helped.
> 
> total loops in shared programs: 629 -> 631 (0.32%)
> loops in affected programs: 0 -> 2
> helped: 0
> HURT: 2
> 
> total fills in shared programs: 93 -> 94 (1.08%)
> fills in affected programs: 81 -> 82 (1.23%)
> helped: 0
> HURT: 1
> 
> LOST:   55
> GAINED: 55
> 
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