The longest running time of single clEnqueueNDRangeKernel() is about 1166 ms.<div>The shortest running time of single clEnqueueNDRangeKernel() is about 335 ms.</div><div>dmesg doesn't give GPU hang hint.</div><div><br></div><div>Using the same data which is decrypted wrong in testing, it will be right if I compute it again in a split program, which is only responsible for decryption. And the probability of computation fault is only about 1% in benchmark testing. So, I think <span style="color: rgb(31, 73, 125); font-family: Calibri, sans-serif; font-size: 14.6667px;">ECC (Error Correcting Codes) would be the reason now, or some other reasons which are similar to this.</span><br><br><blockquote name="replyContent" class="ReferenceQuote" style="padding-left:5px;margin-left:5px;border-left:#b6b6b6 2px solid;margin-right:0">-----原始邮件-----<br>
<b>发件人:</b><span id="rc_from">"Yang, Rong R" <rong.r.yang@intel.com></span><br>
<b>发送时间:</b><span id="rc_senttime">2017-04-13 16:36:07 (星期四)</span><br>
<b>收件人:</b> "Song, Ruiling" <ruiling.song@intel.com>, "Gao, Sanshan" <gss@mail.ustc.edu.cn>, "beignet@lists.freedesktop.org" <beignet@lists.freedesktop.org><br>
<b>抄送:</b> <br>
<b>主题:</b> RE: [Beignet] Random error with very low prabability in Haswell platform<br><br>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">How long don’t your benchmark run?<a name="_MailEndCompose" target="_blank"> Does linux kernel reset the GPU? You could run `dmesg` to get this information.<o:p></o:p></a></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><a name="_____replyseparator" target="_blank"></a><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Beignet [mailto:<a href="mailto:beignet-bounces@lists.freedesktop.org" target="_blank">beignet-bounces@lists.freedesktop.org</a>]
<b>On Behalf Of </b>Song, Ruiling<br>
<b>Sent:</b> Tuesday, April 11, 2017 9:22<br>
<b>To:</b> Gao, Sanshan <<a href="mailto:gss@mail.ustc.edu.cn" target="_blank">gss@mail.ustc.edu.cn</a>>; <a href="mailto:beignet@lists.freedesktop.org" target="_blank">beignet@lists.freedesktop.org</a><br>
<b>Subject:</b> Re: [Beignet] Random error with very low prabability in Haswell platform<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Do you mean the ECC (Error Correcting Codes) on Intel GPU by “hardware mistakes”?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Intel GPU adds one bit ECC support to L3 Cache since Broadwell. For details, you can look at:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><a href="https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-bdw-vol07-3d_media_gpgpu_3.pdf" target="_blank">https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-bdw-vol07-3d_media_gpgpu_3.pdf</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I am not sure whether you problem is caused by the lack of ECC for L3 cache on Haswell.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">But I think it may help you if you can find a Broadwell machine to do some testing.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Ruiling<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Beignet [<a href="mailto:beignet-bounces@lists.freedesktop.org" target="_blank">mailto:beignet-bounces@lists.freedesktop.org</a>]
<b>On Behalf Of </b>Gao, Sanshan<br>
<b>Sent:</b> Friday, April 7, 2017 4:47 PM<br>
<b>To:</b> <a href="mailto:beignet@lists.freedesktop.org" target="_blank">beignet@lists.freedesktop.org</a><br>
<b>Subject:</b> [Beignet] Random error with very low prabability in Haswell platform<o:p></o:p></span></p>
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<p class="MsoNormal">Hi, all,<o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal">Platform: Intel Iris Pro Graphics 5200, OpenCL, Beignet<o:p></o:p></p>
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<p class="MsoNormal">Grandtruth: computed reuslt by OpenSSL library<o:p></o:p></p>
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<p class="MsoNormal">Thanks,<o:p></o:p></p>
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<p class="MsoNormal">Sanshan<o:p></o:p></p>
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