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    SubjectRe: [PATCH 1/3] padata: separate serial and parallel cpumasks
    On Fri, Jul 2, 2010 at 1:32 PM, Dan Kruchinin <> wrote:
    > On Fri, Jul 2, 2010 at 1:17 PM, Steffen Klassert
    > <> wrote:
    >> On Fri, Jul 02, 2010 at 01:07:44PM +0400, Dan Kruchinin wrote:
    >>> >
    >>> ...
    >> But the active cpumask, and now also your serial cpumask might change.
    >> We need to catch this changes somehow, that's why I checked the active
    >> cpumask against the callback cpu.
    > You're right, now I get it. Hence the right solution is to check if
    > callback CPU is set in serial cpumask every time we do
    > padata_do_serial and if it's not, recalculate its value.

    padata_do_parallel of course.

    > The only thing that embarrasses me in this scheme is the fact that we
    > have to allocate cpumask_var_t in pcrypt_do_parallel every time we
    > call it then copy serial cpumask into allocated one and then check the
    > cb_cpu.
    > I think it would be better if we somehow could avoid dynamic cpumask
    > allocation. I see the following solutions:
    > 1) Do the check and cb_cpu value recalculation in padata_do_parallel.
    > It may check if cb_cpu is in serial_cpumask and recalculate its value
    > if it isn't. The drawback of this scheme is that padata_do_parallel
    > now doesn't guaranty it will forward serialization job to the same
    > callback CPU we passed to it. If passed CPU is not in serial cpumask
    > it will forward serialization to another CPU and we won't know its
    > number. The only thing we'll know is that this CPU is in the
    > serial_cpumask.
    > 2) Create new structure describing pcrypt instance in pcrypt.c which
    > will include waitqueue, padata instance and preallocated cpumask which
    > will be used for getting padata instance serial cpumsak. It'll help to
    > avoid dynamic cpumask allocation but it looks a bit awkward.
    >> Steffen
    > --
    > W.B.R.
    > Dan Kruchinin

    Dan Kruchinin

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