x86_64 assembly pack: "optimize" for Knights Landing. #4006
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"Optimize" is in quotes because it's rather a "salvage operation" for now. Idea is to identify processor capability flags that drive Knights Landing to suboptimial code paths and mask them. Two flags were identified, XSAVE and ADCX/ADOX. Former affects choice of AES-NI code path specific for Silvermont (Knights Landing is of Silvermont "ancestry"). And 64-bit ADCX/ADOX instructions are effectively mishandled at decode time. In both cases we are looking at ~2x improvement. Hardware used for benchmarking courtesy of Atos, experiments run by Romain Dolbeau <romain.dolbeau@atos.net>. Kudos! This is minimalistic backpoint of 64d92d7
richsalz
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Jul 24, 2017
Thanks to David Benjamin for spotting typo in Knights Landing detection!
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This needs re-approval because of typo fixed in #4009. |
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re-approval |
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"Optimize" is in quotes because it's rather a "salvage operation" for now. Idea is to identify processor capability flags that drive Knights Landing to suboptimial code paths and mask them. Two flags were identified, XSAVE and ADCX/ADOX. Former affects choice of AES-NI code path specific for Silvermont (Knights Landing is of Silvermont "ancestry"). And 64-bit ADCX/ADOX instructions are effectively mishandled at decode time. In both cases we are looking at ~2x improvement. Hardware used for benchmarking courtesy of Atos, experiments run by Romain Dolbeau <romain.dolbeau@atos.net>. Kudos! This is minimalistic backpoint of 64d92d7 Thanks to David Benjamin for spotting typo in Knights Landing detection! Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #4006)
levitte
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that referenced
this pull request
Jul 25, 2017
"Optimize" is in quotes because it's rather a "salvage operation" for now. Idea is to identify processor capability flags that drive Knights Landing to suboptimial code paths and mask them. Two flags were identified, XSAVE and ADCX/ADOX. Former affects choice of AES-NI code path specific for Silvermont (Knights Landing is of Silvermont "ancestry"). And 64-bit ADCX/ADOX instructions are effectively mishandled at decode time. In both cases we are looking at ~2x improvement. Hardware used for benchmarking courtesy of Atos, experiments run by Romain Dolbeau <romain.dolbeau@atos.net>. Kudos! This is minimalistic backpoint of 64d92d7 Thanks to David Benjamin for spotting typo in Knights Landing detection! Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #4006) (cherry picked from commit 738a9dd)
pracj3am
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Aug 22, 2017
"Optimize" is in quotes because it's rather a "salvage operation" for now. Idea is to identify processor capability flags that drive Knights Landing to suboptimial code paths and mask them. Two flags were identified, XSAVE and ADCX/ADOX. Former affects choice of AES-NI code path specific for Silvermont (Knights Landing is of Silvermont "ancestry"). And 64-bit ADCX/ADOX instructions are effectively mishandled at decode time. In both cases we are looking at ~2x improvement. Hardware used for benchmarking courtesy of Atos, experiments run by Romain Dolbeau <romain.dolbeau@atos.net>. Kudos! This is minimalistic backpoint of 64d92d7 Thanks to David Benjamin for spotting typo in Knights Landing detection! Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from openssl#4006)
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"Optimize" is in quotes because it's rather a "salvage operation"
for now. Idea is to identify processor capability flags that
drive Knights Landing to suboptimial code paths and mask them.
Two flags were identified, XSAVE and ADCX/ADOX. Former affects
choice of AES-NI code path specific for Silvermont (Knights Landing
is of Silvermont "ancestry"). And 64-bit ADCX/ADOX instructions are
effectively mishandled at decode time. In both cases we are looking
at ~2x improvement.
Hardware used for benchmarking courtesy of Atos, experiments run by
Romain Dolbeau romain.dolbeau@atos.net. Kudos!
This is minimalistic backpoint of 64d92d7
1.1.0 and 1.0.2-sprecific follow-up to #3972.