Definitely using an Intel processor (2.6 GHz Intel Core i7), and I heard about this as well. That’s what makes it so surprising.
Gabe > On Apr 26, 2015, at 3:23 PM, Jeffrey Walton <[email protected]> wrote: > > > > On Thursday, April 23, 2015 at 10:14:01 PM UTC-4, Gabriel Hackebeil wrote: > I've run the benchmark tests after compiling Crypto++ 5.6.2 with the latest > versions of the Intel compilers (icpc 15.0.2), GNU g++ (4.9 and 5.1), and > Clang (Apple LLVM version 6.1.0). I'm basically interested in getting the > best possible performance for AES in CTR mode, and the results of the > benchmarks were surprising. In my limited understanding, use of the AES-NI > instruction set (which I believe only the Intel compiler can utilize) is > supposed to provide a big performance boost for AES. The results do not show > this. For the AES mode of interest (CTR), the throughput I achieve (as > reported by the benchmark test suite) is roughly: > > Clang: ~1 GiB/second > Intel: ~1.7 GiB/second > GNU: ~4.1 GiB/second > > Can someone explain why GNU has such a huge boost in performance (~2.5x) over > Intel, when GNU can not use the AES-NI instructions (I don't care much about > Clang)? I get the same results comparing Intel and GNU on a Linux VM. Let me > know if you need any relevant machine specs (Intel core i7 cpu). The relevant > compiler flags appearing on Linux vs OS X are shown below (the performance > results are the same on either operation system and I've played with various > optimization flags for each without much change in performance). Can anyone > enlighten me about the lack of performance boost from AES-NI? > > It may depend on your processor. Are you using an Intel processor, or an AMD > (or other) processor. > > Intel has been known to do sneaky things, like provide sub-optimal code on > non-Intel processors. Way back when when Intel was caught doing this, they > did not stop doing it. Rather, they informed developers they were doing it to > side step consumer protection laws. See, for example, > http://www.agner.org/optimize/blog/read.php?i=49#49 or > https://www.google.com/search?q=intel+bad+code+on+amd. > > -- > -- > You received this message because you are subscribed to the "Crypto++ Users" > Google Group. > To unsubscribe, send an email to [email protected]. > More information about Crypto++ and this group is available at > http://www.cryptopp.com <http://www.cryptopp.com/>. > --- > You received this message because you are subscribed to a topic in the Google > Groups "Crypto++ Users" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/cryptopp-users/tY6yg7da6kk/unsubscribe > <https://groups.google.com/d/topic/cryptopp-users/tY6yg7da6kk/unsubscribe>. > To unsubscribe from this group and all its topics, send an email to > [email protected] > <mailto:[email protected]>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- -- You received this message because you are subscribed to the "Crypto++ Users" Google Group. To unsubscribe, send an email to [email protected]. More information about Crypto++ and this group is available at http://www.cryptopp.com. --- You received this message because you are subscribed to the Google Groups "Crypto++ Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
