Re: [Xen-devel] freezing of kernel threads

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.11.12 at 17:47, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> On Thu, Nov 22, 2012 at 11:21:30AM +0000, Jan Beulich wrote:
>> Keir,
>> 
>> in linux-2.6.18-xen.hg c/s 74:cb50d25a9468 you made blktap
>> match blkback in calling try_to_freeze() from the main thread loop.
>> Threads in other drivers didn't get changed, though. Is there a
>> particular reason why only block, and only backend, threads are in
>> need of this (the only other one using it is xenfb_thread())?
>> 
>> Konrad, as of 2.6.23 kernel threads are non-freezable by default,
>> i.e. xen-blkback calling try_to_freeze() is completely pointless
>> without a prior call to set_freezable(). Also, in case the latter is to
>> be added, switching to wait_event_freezable() instead of the
>> direct use of try_to_freeze() might be the right way to go.
> 
> OK, any idea why the need to be come freezable was added in? Just
> for power suspend/resume?

No, which is why I had asked Keir (who unfortunately didn't recall
either).

Jan


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