Messages in this thread | | | Date | Wed, 17 Jan 2018 23:00:37 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context |
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On Wed, 17 Jan 2018, Linus Torvalds wrote:
> On Wed, Jan 17, 2018 at 1:54 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > > raise_softirq() -> raise_softirq_irqoff() > > > > set_softirq_bit(); > > > > if (!in_interrupt()) > > wake_softirqd(); > > > > So if the caller is not in hard or soft interrupt context, which includes > > bottom half disabled regions softirqd is woken. > > That does seem unnecessarily expensive, and maybe we could just do it > with thread flag (TIF_NOTIFY_RESUME or whatever). > > In fact, that was what I *thought* we did. Maybe I just remember some > historical behavior. > > Since networking seems to largely prefer softirqd anyway, maybe that > wake_softirqd() is the right thing to do anyway.
Well, but we only do it when we are not in a bh disabled region. The places where thread context raises the network softirqs is usually inside a bh disabled region, so the softirq is executed on local_bh_enable(). The thread is woken up rarely.
Thanks,
tglx
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