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    SubjectRe: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context
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    On Fri, 2018-01-12 at 09:26 -0800, Linus Torvalds wrote:
    > On Fri, Jan 12, 2018 at 2:13 AM, Peter Zijlstra <peterz@infradead.org> wrote:
    > > On Fri, Jan 12, 2018 at 06:23:08AM +0100, Mike Galbraith wrote:
    > >>
    > >> How would that be better than what RT used to do, and I still do for my
    > >> RT kernels via boot option, namely split ksoftirqd into per-softirq
    > >> threads.
    > >
    > > Since we mention it; one of the problems RT has is that all RX is
    > > through a single softirq context, which generates a priority inversion
    > > between devices.
    >
    > Oh, yes, that is complete and utter shit. Not acceptable at all.
    >
    > As mentioned, it really would need to be per-cpu _and_ per-softirq.
    >
    > Which is why I thought workqueues might be the thing. Whatever RT is
    > doing is apparently just pure and utter garbage.

    Nah, a misunderstanding happened.  RT that still offers full threading
    creates per-softirq threads per cpu.  The regular trees split ksoftirqd
    into only two threads per cpu, one processes timer/hrtimer softriqs,
    the other processes the rest.

    -Mike

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