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Incorrect function ranking? #33

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ajraymond opened this issue Jul 22, 2015 · 1 comment
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Incorrect function ranking? #33

ajraymond opened this issue Jul 22, 2015 · 1 comment

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@ajraymond
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I am witnessing a strange behavior on my machine wrt arch ranking. I've narrowed it down to lib/volk_rank_archs.c:101.

The code does a popcnt on impl_deps, which contains 1 << various LV_{GENERIC,SSE4_1,AVX} constants, and picks the arch with the most 1s. However, since they are powers of two, they all get the same score.

Now, simply getting rid of popcnt solves the problem (as the best archs have a higher LV_ number), but I'm not sure that's the right thing to do
n-west added a commit to n-west/volk that referenced this issue Jul 24, 2015
@n-west
prefs: select highest val kernel when no prefs exist
a877358 
Address issue gnuradio#33
@n-west
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n-west commented Jul 24, 2015

You're correct about this behavior. However, it's only a problem when you don't have a volk_config (generated by volk_profile). I removed the popcnt and will push a fix with the upcoming release.

@n-west n-west closed this as completed Jul 30, 2015
@jdemel jdemel mentioned this issue Jun 1, 2016
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jessica-iwamoto added a commit to jessica-iwamoto/volk that referenced this issue Jul 17, 2018
@jessica-iwamoto
Merge pull request gnuradio#33 in GNSSSDR/volk from bugfix/GNSSSDR-95…
4ac76fc 
…-fma-trig-functions to next

* commit '6ec8fdb8194657d451c4bcc5f798e6ea56da51ad':
  bugfix: Put FMA intrinsics in separate protokernel for sin and cos functions
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@ajraymond @n-west