[linux-cifs-client] high system load and processes stuck in iowait with CIFS mount

Timothee Besset ttimo at idsoftware.com
Wed Apr 16 15:51:30 GMT 2008


Debian Etch x86, with stock 2.6.18 kernel, also happening with a custom kernel:

I have a nice'd backup process that writes out data using a CIFS mount
to a remote/offsite host. The connection to the remote host isn't very
fast, and I don't mind that it takes a long time to run.

The problem is that it kills performance on everything else on the
system when running. I see the load average going very high (~10) but
very little actual CPU usage. Processes that are unrelated to the backup
get stuck on iowait / disk sleep for very long periods at a time, making
the entire system unresponsive. Even logging into the system takes up to
a minute because processes that need to do any filesystem access will
get stuck for a while.

I understand that an offsite CIFS mount is far from ideal for backup
connectivity. The backup utility I'm using (duplicity) doesn't have a
"direct to CIFS" backend and I can't get something else for offsite
storage from my company, so I'm stuck with a CIFS filesystem mount.

Is there anything I can do to avoid the CIFS access hurting everything else?


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