[Linux-cluster] GFS2 locking in a VM based cluster (KVM)

[Thomas Sjolshagen]

Hi,

Posted this on IRC just now, but was recommended to try another approach.

I'm wondering if the locks/sec rate I'm seeing between two virtual  
machines is what I should expect - details below:

I've got a 2-node cluster that is actually two KVM VMs (Fedora 14 in  
the guests/vms). Between the two VM's, I'm sharing - iSCSI based  
external array using virtio_net drivers in the guests/vms - two GFS2  
file systems. After setting <dlm> and <gfs_controld> as listed below  
in cluster.conf (and, of course, rebooting the whole cluster), I'm  
still only seeing 600-650 locks/sec when using the ping_pong utility.

<dlm plock_ownership="1" plock_rate_limit="0" protocol="sctp"/>
<gfs_controld plock_rate_limit="0"/>

The same settings & configuration on the physical hosts (a separate  
cluster, but using the same iSCSI array) is seeing 5.5-6K locks/sec.

I'm also curious as to why, when starting ping_pong on the virtualized  
node1, I see ~20-40K locks/sec, but if I start and then stop ping_pong  
on the virtualized node2, node1 never returns to anything close to the  
20-40K locks/sec. Is that (also) expected?

Both physical & virtual machines are running Fedora 14  
w/gfs2-utils-3.1.0-3.fc14.x86_64 & gfs2-cluster-3.1.0-3.fc14.x86_64.

// Thomas

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