On Mon, Apr 6, 2009 at 8:27 PM, Tomasz Chmielewski <mangoo at wpkg.org> wrote: > Note that crypt performance for SCST was worse than that of STGT for large > read-ahead values. > Also, SCST performance on crypt device was more or less the same with 256 > and 16384 readahead values. I wonder why performance didn't increase here > while increasing readahead values? Could anyone recheck if it's the same on > some other system? I have repeated the test for the non-encrypted case. Setup details: * target: 2.6.29.1 kernel, 64-bit, Intel E8400 CPU @ 3 GHz, 4 GB RAM, two ST3250410AS disks, with /dev/md3 set up in RAID-1 with a stripe size of 32 KB, local reading speed of /dev/md3: 120 MB/s, I/O scheduler: CFQ. * initiator: 2.6.28.7 kernel, 64-bit, Intel E6750 CPU @ 2.66 GHz, 2 GB RAM. * network: 1 Gbit/s Ethernet, two systems connected back to back via a crossed cable. Each test was repeated four times. Before each test the target caches were dropped via the command "sync; echo 3 > /proc/sys/vm/drop_caches". The following test has been run on the initiator: sync; echo 3 > /proc/sys/vm/drop_caches; dd if=/dev/sdb of=/dev/null bs=64K count=100000 Results with read-ahead set to 256 on the initiator, in MB/s: STGT 56.7 +/- 0.3 SCST 56.9 +/- 1.1 Results with read-ahead set to 16384 on the initiator, in MB/s: STGT 59.9 +/- 0.1 SCST 59.5 +/- 0.0 Or: slightly better results with the larger read-ahead value, and a performance difference well below 1% between the STGT and SCST performance results. Bart. -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html |