Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses.

From: Pavel Machek
Date: Mon Dec 05 2016 - 05:33:38 EST


Hi!

> >>In the ring, some descriptors can raise the irq (according to a
> >>threshold) and set the IC bit. In this path, the NAPI poll will be
> >>scheduled.
> >
> >Not NAPI poll but stmmac_tx_timer(), right?
>
> in the xmit according the the threshold the timer is started or the
> interrupt is set inside the descriptor.
> Then stmmac_tx_clean will be always called and, if you see the flow,
> no irqlock protection is needed!

Actually, I was wrong. irqlock protection is needed, since
stmmac_tx_clean() is called from timer, and that's interrupt context,
as you can confirm using BUG_ON(in_interrupt());

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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