Bart Van Assche schrieb: > On Mon, Apr 6, 2009 at 12:29 PM, Tomasz Chmielewski <mangoo at wpkg.org> wrote: >> The target is running Debian Lenny 64bit userspace on an Intel Celeron >> 2.93GHz CPU, 2 GB RAM. >> >> Initiator is running Debian Etch 64 bit userspace, open-iscsi 2.0-869, Intel >> Xeon 3050/2.13GHz, 8 GB RAM. >> >> >> Each test was repeated 6 times, "sync" was made and caches were dropped on >> both sides before each test was started. >> >> dd parameters were like below, so 6.6 GB of data was read each time: >> >> dd if=/dev/sdag of=/dev/null bs=64k count=100000 >> >> >> Data was read from two block devices: >> - /dev/md0, which is RAID-1 on two ST31500341AS 1.5 TB drives >> - encrypted dm-crypt device which is on top of /dev/md0 >> >> Encrypted device was created with the following additional options passed to >> cryptsetup >> (it provides the most performance on systems where CPU is a bottleneck, but >> with decreased >> security when compared to default options): >> >> -c aes-ecb-plain -s 128 >> >> >> Generally, CPU on the target was a bottleneck, so I also tested the load on >> target. >> >> >> md0, crypt columns - averages from dd >> us, sy, id, wa - averages from vmstat >> >> >> 1. Disk speeds on the target >> >> Raw performance: 102.17 MB/s >> Raw performance (encrypted): 50.21 MB/s >> >> >> 2. Read-ahead on the initiator: 256 (default); md0, crypt - MB/s >> >> md0 us sy id wa | crypt us sy id wa >> STGT 50.63 4% 45% 18% 33% | 32.52 3% 62% 16% 19% >> SCST (debug + no patches) 43.75 0% 26% 30% 44% | 42.05 0% 84% 1% 15% >> SCST (fullperf + patches) 45.18 0% 25% 33% 42% | 44.12 0% 81% 2% 17% > > Hello Tomasz, > > How is it possible that for this test the read performance through > STGT (50.63 MB/s) was higher than the read performance on the target > (50.21 MB/s) ? Are you sure that all read buffers were flushed before > this test was started ? You're looking at wrong columns: md0 crypt STGT 50.63 32.52 RAW 102.17 50.21 -- Tomasz Chmielewski http://wpkg.org -- 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 |