[dm-devel] cmwq and dm-crypt devices?
Tejun Heo
tj at kernel.org
Wed Nov 3 16:17:40 UTC 2010
Hello,
On 11/03/2010 05:13 PM, Andi Kleen wrote:
>> Please fix this regression the patch causes then or give some
>> fundamental arguments why we can't satisfy the two requirements
>> simultaneously: I just don't understand why it is necessary to cause a
>> regression in stacking/low memory support in order to provide the
>> performance boost in the way you desire. The two things ought to be
>> independent of each other.
>
> The old stacking relies on per device threads. Per device threads
> cannot be combined with per CPU threads, because that would lead
> to a thread explosion for large device counts.
Dunno the context here but creating WQ_NON_REENTRANT | WQ_MEM_RECLAIM
workqueue per device should achieve what you want. It will be per-cpu
while reserving only one worker per workqueue, so there won't be
explosion of threads.
Thanks.
--
tejun
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