[Gluster-devel] [Qusetions] How profile affect glusterfs performance?

[Xie Changlong]

Hi all

It's said[1] that profile based on io-stats, if you enable this feature, 
it can affect system performance while the profile information is being 
collected.

I do some tests on my two linux+vmware virtual machine with replica(lack 
of resources ). And the results shows no diffrence to me, following is 
the test case
#dd if=/dev/zero  of=test bs=4k count=524288
#fio --filename=test -iodepth=64 -ioengine=libaio --direct=1 --rw=read 
--bs=1m --size=2g --numjobs=4 --runtime=10 --group_reporting 
--name=test-read
#fio -filename=test -iodepth=64 -ioengine=libaio -direct=1 -rw=write 
-bs=1m -size=2g -numjobs=4 -runtime=20 -group_reporting -name=test-write
#fio -filename=test -iodepth=64 -ioengine=libaio -direct=1 -rw=randread 
-bs=4k -size=2G -numjobs=64 -runtime=20 -group_reporting 
-name=test-rand-read
#fio -filename=test -iodepth=64 -ioengine=libaio -direct=1 -rw=randwrite 
-bs=4k -size=2G -numjobs=64 -runtime=20 -group_reporting 
-name=test-rand-write
It's said that fio is only for lagre files, also i suspect that the test 
infrastructure is too small. The question is that, if you guys have 
detailed data for how profile affect performance?

More, we wanna gain the detail r/w iops/bandwidth data for each brick. 
It seems that only profile can provide relatived data to be 
calculated?if i'm wrong pls corrent me.

If profile really affect peformance so much, would you mind a new 
command such as "gluster volume io [nfs]" to acquire brick r/w 
fops/data? Or just help us review it?

[1] 
https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.2/html/administration_guide/chap-monitoring_red_hat_storage_workload#sect-Running_the_Volume_Profile_Command
-- 
Thanks
     -Xie