[Linux-cluster] optimising DLM speed?

Alan Brown ajb2 at mssl.ucl.ac.uk
Thu Feb 17 21:24:41 UTC 2011

David Teigland wrote:
> Don't change the buffer size, but I'd increase all the hash table sizes to
> 4096 and see if anything changes.
> echo "4096" > /sys/kernel/config/dlm/cluster/rsbtbl_size
> echo "4096" > /sys/kernel/config/dlm/cluster/lkbtbl_size
> echo "4096" > /sys/kernel/config/dlm/cluster/dirtbl_size

Increasing rsbtbl_size to 4096 or higher results in FSes refusing to 
mount and clvm refusing to start - both with "cannot allocate memory"

At 2048, it works, but gfs_controld and dlm_controld exited when I tried 
to mount all FSes on one node as a test.

At 1024 it seems stable.

The other settings seemed to have applied OK. So far, reports are 
positive (but it's quiet at the moment)

I've got a strace of clvmd trying to start with rsbtbl_size set to 4096. 
Should I post it here or would you prefer it mailed direct?

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