Matthias Schniedermeyer wrote: > HDD is a 500GB Seagate/PATA, connected to a onboard jmicron > PATA-Controller(apears to be a PCIe device) and driven by the matching > libata driver. The HDD delivers a linear throughput of about 70-73MB/s, > which doesn't decrease much when i put a aes128-v3-loop over it, and > which uses about 1/2 of the available CPU-ressources > > gpg < key.gpg | losetup -e aes128 -p 0 /dev/loop4 /dev/sdb > > The same loop, with the "not good" offsets of 512-3584, decreases the > throughput to a craw of 5-20MB/s (don't have exact numbers anymore and > currently my system is working, so i can't retest) > > With an offset of 4096 everything is good(tm) again. > gpg < key.gpg | losetup -e aes128 -p 0 -o 4096 /dev/loop4 /dev/sdb Did you test it through a file system or direct to loop device? Direct to loop device test has disadvantage of possibly un-optimal default soft block size. If loop device size is not multiple of page size, then smaller than page size soft block size default is set at losetup time. This may affect performance when loop device is read/written directly. File system mount of course sets better soft block size and bangs the device using more optimally sized reguests. Using offset=512 shrinks loop device size. What does "blockdev --getsize /dev/loop4" command output now (using 4096 byte offset)? -- Jari Ruusu 1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9 DB 1D EB E3 24 0E A9 DD - Linux-crypto: cryptography in and on the Linux system Archive: http://mail.nl.linux.org/linux-crypto/
