Increasing GELI performance
Dominic Bishop
dom at bishnet.net
Fri Jul 27 19:57:43 UTC 2007
I've just been testing out GELI performance on an underlying RAID using a
3ware 9550SXU-12 running RELENG_6 as of yesterday and seem to be hitting a
performance bottleneck, but I can't see where it is coming from.
Testing with an unencrypted 100GB GPT partition (/dev/da0p1) gives me around
200-250MB/s read and write speeds to give an idea of the capability of the
disk device itself.
Using GELI with a default 128bit AES key seems to limit at ~50MB/s ,
changing the sector size all the way upto 128KB makes no difference
whatsoever to the performance. If I use the threads sysctl in loader.conf
and drop the geli threads to 1 thread only (instead of the usual 3 it spawns
on this system) the performance still does not change at all. Monitoring
during writes with systat confirms that it really is spawning 1 or 3 threads
correctly in these cases.
Here is a uname -a from the machine
FreeBSD 004 6.2-STABLE FreeBSD 6.2-STABLE #2: Fri Jul 27 20:10:05 CEST 2007
dom at 004:/u1/obj/u1/src/sys/004 amd64
Kernel is a copy of GENERIC with GELI option added
Encrypted partition created using : geli init -s 65536 /dev/da0p1
Simple write test done with: dd if=/dev/zero of=/dev/da0p1.eli bs=1m
count=10000 (same as I did on the unencyrpted, a full test with bonnie++
shows similar speeds)
Systat output whilst writing, showing 3 threads:
/0 /1 /2 /3 /4 /5 /6 /7 /8 /9 /10
Load Average ||||
/0 /10 /20 /30 /40 /50 /60 /70 /80 /90 /100
root idle: cpu3 XXXXXXXXX
root idle: cpu1 XXXXXXXX
<idle> XXXXXXXX
root idle: cpu0 XXXXXXX
root idle: cpu2 XXXXXX
root g_eli[2] d XXX
root g_eli[0] d XXX
root g_eli[1] d X
root g_up
root dd
Output from vmstat -w 5
procs memory page disks faults cpu
r b w avm fre flt re pi po fr sr ad4 da0 in sy cs us sy
id
0 1 0 38124 3924428 208 0 1 0 9052 0 0 0 1758 451 6354 1
15 84
0 1 0 38124 3924428 0 0 0 0 13642 0 0 411 2613 128 9483 0
22 78
0 1 0 38124 3924428 0 0 0 0 13649 0 0 411 2614 130 9483 0
22 78
0 1 0 38124 3924428 0 0 0 0 13642 0 0 411 2612 128 9477 0
22 78
0 1 0 38124 3924428 0 0 0 0 13642 0 0 411 2611 128 9474 0
23 77
Output from iostat -x 5
extended device statistics
device r/s w/s kr/s kw/s wait svc_t %b
ad4 2.2 0.7 31.6 8.1 0 3.4 1
da0 0.2 287.8 2.3 36841.5 0 0.4 10
pass0 0.0 0.0 0.0 0.0 0 0.0 0
extended device statistics
device r/s w/s kr/s kw/s wait svc_t %b
ad4 0.0 0.0 0.0 0.0 0 0.0 0
da0 0.0 411.1 0.0 52622.1 0 0.4 15
pass0 0.0 0.0 0.0 0.0 0 0.0 0
extended device statistics
device r/s w/s kr/s kw/s wait svc_t %b
ad4 0.0 0.0 0.0 0.0 0 0.0 0
da0 0.0 411.1 0.0 52616.2 0 0.4 15
pass0 0.0 0.0 0.0 0.0 0 0.0 0
Looking at these results myself I cannot see where the bottleneck is, I
would assume since changing the sector size or the geli threads doesn't
affect performance that there is some other single threaded part limiting it
but I don't know enough about how it works to say what.
CPU in the machine is a pair of these:
CPU: Intel(R) Xeon(R) CPU 5110 @ 1.60GHz (1603.92-MHz K8-class
CPU)
I've also come across some other strange issues with some other machines
which have identical arrays but only a pair of 32bit 3.0Ghz xeons in them
(Also using releng_6 as of yesterday, just i386 not amd64). On those geli
will launch a single thread by default (cores-1 seems to be the default)
however I cannot force it to launch 2 by using the sysctl, although on the 4
core machine I can successfully use it to launch 4. It would be nice to be
able to use both cores on the 32bit machines for geli but given the results
I've shown here I'm not sure it would gain me much at the moment.
Another problem I've found is that if I use a sector size for GELI > 8192
bytes then I'm unable to newfs the encrypted partition afterwards, it fails
immediately with this error:
newfs /dev/da0p1.eli
increasing block size from 16384 to fragment size (65536)
/dev/da0p1.eli: 62499.9MB (127999872 sectors) block size 65536, fragment
size 65536
using 5 cylinder groups of 14514.56MB, 232233 blks, 58112 inodes.
newfs: can't read old UFS1 superblock: read error from block device: Invalid
argument
The underlying device is readable/writeable however as dd can read/write to
it without any errors.
If anyone has any suggestions/thoughts on any of these points it would be
much appreciated, these machines will be performing backups over 1Gbit LAN
so more speed than I can currently get would be preferable.
Regards,
Dominic Bishop
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