Hey,
many thanks for your feedback. It seems the crypto step is the culprit:
Reading 1.1 GB with dd, iflag=direct, bs=8k:
/dev/sd* 35.3 MB/s ( 90 %)
/dev/md* 39.1 MB/s (100 %)
/dev/mapper/md*_crypt 3.9 MB/s ( 10 %)
/dev/mapper/vg1-* 3.9 MB/s ( 10 %)
The "good" news: it also happens on my notebook, even though it has a
different setup (no raid, disk -> lv/vg -> crypt). On my notebook, I'm
more than happy to test out different kernel versions, patches etc.
/dev/sd* 17.7 MB/s (100 %)
/dev/mapper/vg1-* 16.2 MB/s ( 92 %)
/dev/mapper/*_crypt 3.1 MB/s ( 18 %)
On a different system, a friend of mine reported (with 2.6.33):
/dev/sd* 51.9 MB/s (100 %)
dm-crypt 32.9 MB/s ( 64 %)
This shows that the speed drop when using dmcrypt is not always a factor of
5 to 10... Btw, it occurs both with aes-lrw-benbi and aes-cbc-essiv:sha256 ,
and (on my notebook) the CPU is mostly idling or waiting.
Best,
Dominik
PS: Bonnie output:
Writing intelligently...done
Rewriting...done
Reading intelligently...done
start 'em...done...done...done...
Create files in sequential order...done.
Stat files in sequential order...done.
Delete files in sequential order...done.
Create files in random order...done.
Stat files in random order...done.
Delete files in random order...done.
Version 1.03d ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
ABCABCABCABCABC 16G 60186 4 24796 4 53386 5 281.1 1
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 3176 16 +++++ +++ 4641 28 5501 20 +++++ +++ 2286 9
ABCABCABCABCABCABC,16G,,,60186,4,24796,4,,,53386,5,281.1,1,16,3176,16,+++++,+++,4641,28,5501,20,+++++,+++,2286,9
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