Hi, On Saturday, 12 May 2007 21:17, Pavel Machek wrote: > Hi! > > > Having considered the issue of freezing (or not freezing) kernel threads > > for a > > longer while I tend to agree with Linus that we shouldn't be freezing as > > many > > kernel threads as we currently freeze, but there's one thing that he doesn't > > seem to take into account. Namely, there may be some kernel threads that > > actually *want* (or need) to be frozen. :-) > > > > For the suspend they may be kernel threads that otherwise would need some > > special synchronization with some device drivers' .suspend() and .resume() > > callbacks or fs-related kernel threads. For the CPU hotplug they might be > > kernel threads that otherwise would interfere with the removal or addition > > of > > CPUs. Still, in each case there seems to be a limited group of kernel > > threads > > that may want to be frozen and the remaining kernel threads that shouldn't > > be > > involved in any freezer-related actions at all. However, we currently > > require > > all kernel threads to take part in the freezing mechanism, which doesn't > > seem to > > be correct. > > Well.. It is actually a feature. > > These days, you have to either add PF_NOFREEZE explicitly (which > hopefully means you know what you are doing) or add try_to_freeze() at > specific place. > > If you fail to do that, we'll see freezer failure, quickly, and catch > the simple bug.
Well, not if PF_NOFREEZE is used. > I'm afraid that if we default to "do not freeze by default", someone > will just port zfs, will know nothing about suspend, and his > "write management info somewhere periodically" thread will corrupt > people's disks. We'll have exactly the same result right now if said developer uses PF_NOFREEZE. > OTOH... perhaps suspend/resume is common enough operation that people > _know_ they need to stop their writing? ...no, I do not think we are > there yet. We never will be there if we don't change the default. Besides, if a kernel thread calls I_want_to_be_frozen_during_suspend() and then try_to_freeze(), this seems to be a bit more meaningful than just calling try_to_freeze() which (almost) everybody does. Greetings, Rafael - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
