[Beignet] Random error with very low prabability in Haswell platform

[Song, Ruiling]

Do you mean the ECC (Error Correcting Codes) on Intel GPU by “hardware mistakes”?
Intel GPU adds one bit ECC support to L3 Cache since Broadwell. For details, you can look at:
https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-bdw-vol07-3d_media_gpgpu_3.pdf
I am not sure whether you problem is caused by the lack of ECC for L3 cache on Haswell.
But I think it may help you if you can find  a Broadwell machine to do some testing.

Thanks!
Ruiling
From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of Gao, Sanshan
Sent: Friday, April 7, 2017 4:47 PM
To: beignet at lists.freedesktop.org
Subject: [Beignet] Random error with very low prabability in Haswell platform

Hi, all,

I'm using Intel Iris Pro Graphics 5200 for general purpose computing, RSA decryption with OpenCL. However, I found that the calculated result would be wrong with very low probability in benchmark. In my experiments, this prabbility is bout "1%". And when I write out this cipher message to a file, which is not decrypted rightly in benchmark, and decrypt it individually, the result becomes right.

Did someone else meet similar situation? I guess there would be some problems with this integrated GPGPU (i.e. there are some mistakes with hardware platform, but not software implementation). I remembered that I heared of such deduction before, but I ignored it, because I had not met such error.

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Platform: Intel Iris Pro Graphics 5200, OpenCL, Beignet
Grandtruth: computed reuslt by OpenSSL library
--------------

Thanks,
Sanshan


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