[vserver] Hard time with IO bottleneck

From: Markus Fischer <markus_at_fischer.name>
Date: Mon 23 Jun 2008 - 18:17:42 BST
Message-ID: <485FDAB6.1070403@fischer.name>


I'm having a hard time with my system when it comes to IO performance.

As an example, I've three directories to delete with about 50000 files in
each. I'm deleting on the "host" system already, using "ionice -c3" (only when
idle) and CFQ scheduler is activated.

While this is done, I've about 11 vserver running.

As long as I have the delete job *not* running, the system has a load < 1.0.
As soon as I start/resume the job, in short the load goes over e.g. 12 !

I'm currently completely puzzled as to what is going on here. Using vtop I
can't find any two processes on top being the cause for the load. The list
usually looks like

   init [2]

continuing with the list of kernel threads and once in a while a process pops
for a second to the top. I already ran vtop with a time interval of 0.l but
the result was the same.

The delete job takes quite some time to finish, probably on the range of an hour.

Even if there would be a major IO bottleneck here with the discs (the whole
host/guest system is located on a LVM on a Primergy RX200 S3) why would it hog
the rest of the system down too, even with ionice idle scheduling?

I'm wondering if this has anything to do anyway with the vserver but I'm
currently completely lost.

- Markus
Received on Mon Jun 23 18:17:57 2008

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