Vladislav Bolkhovitin schrieb: >> 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% >> >> >> 3. Read-ahead on the initiator: 16384; md0, crypt - MB/s >> >> md0 us sy id wa | crypt us sy id >> wa STGT 56.43 3% 55% 2% 40% | 46.90 3% >> 90% 3% 4% >> SCST (debug + no patches) 73.85 0% 58% 1% 41% | 42.70 0% 85% 0% >> 15% >> SCST (fullperf + patches) 76.27 0% 63% 1% 36% | 42.52 0% 85% 0% >> 15% > > Good! You proved that: > > 1. SCST is capable to work much better than STGT: 35% for md and 37% for > crypt considering maximum values. > > 2. Default read-ahead size isn't appropriate for remote data access > cases and should be increased. I slowly have been discussing it in past > few months with Wu Fengguang, the read-ahead maintainer. 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? > Which IO scheduler on the target did you use? I guess, deadline? If so, > you should try with CFQ as well. I used CFQ. -- 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 |