Re: [PATCH] NOHZ: local_softirq_pending with tickless plip

[Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>]

> > Hi
> >
> > On one of my machines with tickless kernel and plip I get messages :
>
> I bet this is a machine a P4 with Hyperthreading enabled ?

No, it's single Pentium 2. I have other Pentium MMX using plip, where I 
don't get these error messages, I don't know why.

Mikulas

> > NOHZ: local_softirq_pending 08
> >
> > always when using plip (on other machine with tickless kernel and plip I
> > get no errors). Thebug happens both on 2.6.21 and 2.6.22-rc1
> >
> > This patch fixes that. Note that plip calls netif_rx neither from hardware
> > interrupt nor from ksoftirqd, so there is no one who would wake
> > ksoftirqd then. netif_tx calls only
> > __raise_softirq_irqoff(NET_RX_SOFTIRQ), which sets softirq bit, but
> > doesn't wake ksoftirqd.
>
> Dave,
>
> can we please get rid of __raise_softirq_irqoff() at all ? These micro
> optimizations are causing more trouble than they are worth.
>
> 	tglx
>
> > Mikulas
> >
> > Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz
> >
> > --- linux-2.6.22-rc1/net/core/dev.c_	Fri May 18 07:51:01 2007
> > +++ linux-2.6.22-rc1/net/core/dev.c	Fri May 18 07:51:06 2007
> > @@ -1117,7 +1117,7 @@
> >   		dev->quota += dev->weight;
> >   	else
> >   		dev->quota = dev->weight;
> > -	__raise_softirq_irqoff(NET_RX_SOFTIRQ);
> > +	raise_softirq_irqoff(NET_RX_SOFTIRQ);
> >   	local_irq_restore(flags);
> >   }
> >   EXPORT_SYMBOL(__netif_rx_schedule);
-
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