Re: [dm-crypt] dm-crypt flush-to-disk freezes

[Milan Broz <mbroz@redhat.com>]

On 08/17/2010 08:46 PM, Arno Wagner wrote:
> The set-up is a dm-crypt partition with a Windows XP 
> VM and the current VMplayer, all with kernel 2.6.34.4
> from kernel.org and current vmware-tools in the VM.

Can you be more specific?

You have direct partition with LUKS and this is mapped
to vmware directly as disk, right?
No fs in the middle?

Are there other encrypted disks on the same underlying
device?

Underlying disk is not SSD, right?

What is the preemption type set in Linux kernel
(Processor type/Preemption model in kernel config)?

What is the IO scheduler for the underlying device?
(You can try deadline or cfq with some tuning - this is
possible to tune online).

Probably tuning fs inside vm can help too. If it is
massive syncing with lot of data waiting for completion,
it is not good.

btw I hope that in 2.6.36 we switch to global workqueues
per cpu for dm-crypt, unfortunately Alasdair is still waiting
with committing it (patches are ready and I am using it myself).
(It can help or it can make it worse here. It needs testing.)

Milan