[Gluster-users] No performance difference using libgfapi?

[Dave Christianson]

Good Morning,

In my earlier experience invoking a VM using qemu/libgfapi, I reported that
it was noticeably faster than the same VM invoked from libvirt using a FUSE
mount; however, this was erroneous as the qemu/libgfapi-invoked image was
created using 2x the RAM and cpu's...

So, invoking the image using both methods using consistent specs of 2GB RAM
and 2 cpu's, I attempted to check drive performance using the following
commands:

(For regular FUSE mount I have the gluster volume mounted at
/var/lib/libvirt/images.)

(For libgfapi I specify -disk file=gluster://gfs-00/gfsvol/tester1/img.)

Using libvirt/FUSE mount:
[root at tester1 ~]# hdparm -Tt /dev/vda1
/dev/vda1:
 Timing cached reads:    11346 MB in 2.00 seconds = 5681.63 MB/sec
 Timing buffered disk reads:    36 MB in 3.05 seconds = 11.80 MB/sec
[root at tester1 ~]# dd if=/dev/zero of=/tmp/output bs=8k count=10k; rm -f
/tmp/output
10240+0 records in
10240+0 records out
41943040 bytes (42MB) copied, 0.0646241 s, 649 MB/sec

Using qemu/libgfapi:
[root at tester1 ~]# hdparm -Tt /dev/vda1
/dev/vda1:
 Timing cached reads:    11998 MB in 2.00 seconds = 6008.57 MB/sec
 Timing buffered disk reads:    36 MB in 3.03 seconds = 11.89 MB/sec
[root at tester1 ~]# dd if=/dev/zero of=/tmp/output bs=8k count=10k; rm -f
/tmp/output
10240+0 records in
10240+0 records out
41943040 bytes (42MB) copied, 0.0621412 s, 675 MB/sec

Should I be seeing a bigger difference, or am I doing something wrong?

I'm also curious whether people have found that the performance difference
is greater as the size of the gluster cluster scales up.

Thanks,
David
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