[Linux-cluster] strange slowness of ls with 1 newly created file on gfs 1 or 2

[Wendy Cheng]

Pavel Stano wrote:

>and then run touch on node 1:
>serpico# touch /d/0/test
>
>and ls on node 2:
>dinorscio:~# time ls /d/0/
>test
>
>  
>

What have you expected from a cluster filesystem ? When you touch a file 
on node 1, it is a "create" that requires at least 2 exclusive locks 
(directory lock and the file lock itself, among many other things). On a 
local filesystem such as ext3, disk activities are delayed due to 
filesystem cache where "touch" writes the data into cache and "ls" reads 
it from cache on the very same node - all memory operations.  On cluster 
filesystem, when you do an "ls" on node 2, node 2 needs to ask node 1 to 
release the locks (few ping-pong messages between two nodes and lock 
managers via network), the contents inside node 1's cache need to get 
synced to the shared storage. After node 2 gets the locks, it  has to 
read contents from the disk.

I hope the above explanation is clear.

>and last thing, i try gfs2, but same result
>
>
>  
>
-- Wendy