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    SubjectRe: [ 00/10] [Suspend2] Modules support.
    Date
    Hi,

    On Saturday 04 February 2006 12:08, Nigel Cunningham wrote:
    > On Saturday 04 February 2006 20:58, Rafael J. Wysocki wrote:
    > > Hi,
    > >
    > > On Saturday 04 February 2006 10:54, Nigel Cunningham wrote:
    > > > On Saturday 04 February 2006 19:01, Pavel Machek wrote:
    > > > > On So 04-02-06 11:20:54, Nigel Cunningham wrote:
    > > > > > Hi Pavel.
    > > > > >
    > > > > > On Friday 03 February 2006 21:44, Pavel Machek wrote:
    > > > > > > [Pavel is willing to take patches, as his cooperation with
    > > > > > > Rafael shows, but is scared by both big patches and series of 10
    > > > > > > small patches he does not understand. He likes patches removing
    > > > > > > code.]
    > > > > >
    > > > > > Assuming you're refering to the patches that started this thread,
    > > > > > what don't you understand? I'm more than happy to explain.
    > > > >
    > > > > For "suspend2: modules support", it is pretty clear that I do not
    > > > > need or want that complexity. But for "refrigerator improvements", I
    > > > > did
    > > >
    > > > ... and yet you're perfectly happy to add the complexity of sticking
    > > > half the code in userspace. I don't think I'll ever dare to try to
    > > > understand you, Pavel :)
    > > >
    > > > > not understand which parts are neccessary because of suspend2
    > > > > vs. swsusp differences, and if there is simpler way towards the same
    > > > > goal. (And thanks for a stress hint...)
    > > >
    > > > I think virtually everything is relevant to you.
    > >
    > > My personal view is that:
    > > 1) turning the freezing of kernel threads upside-down is not necessary
    > > and would cause problems in the long run,
    >
    > Upside down?

    I mean now they should freeze voluntarily and your patches change that
    so they would have to be created as non-freezeable if need be, AFAICT.

    > > 2) the todo lists are not necessary and add a lot of complexity,
    >
    > Sorry. Forgot about this. I liked it for solving the SMP problem, but IIRC,
    > we're downing other cpus before this now, so that issue has gone away. I
    > should check whether I'm right there.
    >
    > > 3) trying to treat uninterruptible tasks as non-freezeable should better
    > > be avoided (I tried to implement this in swsusp last year but it caused
    > > vigorous opposition to appear, and it was not Pavel ;-))
    >
    > I'm not suggesting treating them as unfreezeable in the fullest sense. I
    > still signal them, but don't mind if they don't respond. This way, if they
    > do leave that state for some reason (timeout?) at some point, they still
    > get frozen.

    Yes, that's exactly what I wanted to do in swsusp. ;-)

    > > > A couple of possible exceptions might be (1) freezing bdevs,
    > > > because you don't care so much about making xfs really sync and really
    > > > stop it's activity
    > >
    > > As I have already stated, in my view this one is at least worth
    > > considering in the long run.
    > >
    > > > and (2) the ability to thaw kernel space without thawing userspace. I
    > > > want this for eating memory, to avoid deadlocking against kjournald
    > > > etc. I haven't checked carefully as to why you don't need it in
    > > > vanilla.
    > >
    > > Because it does not deadlock? I will say we need this if I see a
    > > testcase showing such a deadlock clearly.
    >
    > I've been surprised that you haven't already seen them while eating memory
    > such that filesystems come into play. Perhaps you guys only use swap
    > partitions, and something like a swapfile with some memory pressure might
    > trigger this? Or it could be a side effect of one of the other changes.

    In fact, we only use swap partitions, so this will be needed if we are going
    to use files, I guess. Nice to know in advance, thanks. ;-)

    Greetings,
    Rafael
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