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From: | Ron Economos |
Subject: | Re: [Discuss-gnuradio] Non-deterministic behavior in GNU Radio |
Date: | Wed, 3 Oct 2018 06:52:52 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
Ron On 10/03/2018 06:42 AM, Ron Economos wrote:
Well, I guess it's not really a bug. Most likely it has to do with the accuracy difference between the x86 intrinsics and the C library. If you look at the code in volk_32fc_x2_divide_32fc.h, the remaining points that are not a multiple of four are calculated with the C library. If the points from one run that are calculated with the C library line up with points calculated with intrinsics in the next run, there can be a mismatch.Ron On 10/03/2018 06:27 AM, Ron Economos wrote:It's a VOLK bug. Go into ~/.volk/volk_profile and change the volk_32fc_x2_divide_32fc line to generic. That fixes the issue here.Ron On 10/03/2018 05:46 AM, Piotr Krysik wrote:Hi all, I simplified the flowgraph a bit and prepared a script that runs it twice and compares the results. https://imgur.com/a/CSjOeLc In short something is wrong indeed. Almost after every run of the script I get results with differences.I tested it on GNU Radio 3.7.12.0, I'm compiling the most fresh versionnow. Best Regards, Piotr Krysik W dniu 03.10.2018 o 06:55, Reiichiro Nakano pisze:Here's an updated flowgraph where you don't need a separate file source. Just run the flowgraph twice for a few seconds each. You'll likely get different file sizes but `cmp` doesn't care, it'll still show the first differing byte which should still prove the bug exists._______________________________________________ Discuss-gnuradio mailing list address@hidden https://lists.gnu.org/mailman/listinfo/discuss-gnuradio_______________________________________________ Discuss-gnuradio mailing list address@hidden https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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