Bart Van Assche schrieb:
> Hello Tomasz,
>
> It would be great if you could publish the details of your setup and
> the tests you have run, such that we are able to reproduce the tests
> and analyze the results further.
Here it is.
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%
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%
--
Tomasz Chmielewski
http://wpkg.org
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