Results from my 5 year old laptop (X230, Core i5-3320M with 2.6 GHz), for a 1 GB file:
MD5+SHA1+SHA256: 11s => 90 MB/s => 727 Mbit/s MD5+SHA1+SHA256+SHA512: 15s => 67 MB/s => 533 Mbit/s That seems like an acceptable baseline performance. You are not likely to hit GBs worth of packages, so you have like less than 10 seconds of maximum CPU use (likely you'll hit 100-200 MB, so 2-3 seconds of CPU burst). I think 2-3 seconds is completely acceptable. With nettle which is hardware-accelerated, we achieve: MD5+SHA1+SHA256: 9s => 111 MB/s => 888 Mbit/s MD5+SHA1+SHA256+SHA512: 12.8s => 78 MB/s => 625 Mbit/s (Tests might be skewed a bit in favor of apt, as it avoids duplicate reads - I had to run multiple nettle-hash after each other, rather than after each other per block, the overhead is about 0.2 / 0.4s) The improvement does not seem huge. Obviously, if you find faster implementations to contribute to nettle, things might improve further. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/1123272 Title: high cpu usage on download (not optimised SHA256, SHA512, SHA1) Status in apt package in Ubuntu: Confirmed Bug description: http process takes about 20% on intel i5-3317. Here is output of ps aux: root 4309 21.7 0.0 37108 2344 pts/2 S+ 18:17 0:01 /usr/lib/apt/methods/http it can be easy reproduces with "apt-get download firefox-dbg" or any other upgrade realted command. The reason of this overhead are this functions: 22,34% http libapt-pkg.so.4.12.0 [.] SHA256_Transform(_SHA256_CTX*, unsigned int const*) 14,81% http libapt-pkg.so.4.12.0 [.] SHA512_Transform(_SHA512_CTX*, unsigned long const*) 8,11% http libapt-pkg.so.4.12.0 [.] SHA1Transform(unsigned int*, unsigned char const*) 5,62% http libapt-pkg.so.4.12.0 [.] MD5Transform(unsigned int*, unsigned int const*) libapt uses own implementation of this hasches without any optimisation. Are there any reason why libapt do not use openssl? Beside current version of openssl has AVX optimised SHA* implementations. ProblemType: Bug DistroRelease: Ubuntu 13.04 Package: apt 0.9.7.7ubuntu1 ProcVersionSignature: Ubuntu 3.8.0-4.9-generic 3.8.0-rc6 Uname: Linux 3.8.0-4-generic x86_64 ApportVersion: 2.8-0ubuntu4 Architecture: amd64 Date: Tue Feb 12 18:12:33 2013 InstallationDate: Installed on 2012-09-13 (152 days ago) InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120913.1) MarkForUpload: True ProcEnviron: TERM=xterm PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=de_DE.UTF-8 SHELL=/bin/bash SourcePackage: apt UpgradeStatus: Upgraded to raring on 2013-02-06 (5 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1123272/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
