linux-kernel - Re: [PATCH] r8169: Reduce looping in the interrupt handler.

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Message-ID: <20090826213024.GA20428@electric-eye.fr.zoreil.com>
Date:	Wed, 26 Aug 2009 23:30:24 +0200
From:	Francois Romieu <romieu@...zoreil.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	David Dillow <dave@...dillows.org>,
	Michael Riepe <michael.riepe@...glemail.com>,
	Michael Buesch <mb@...sch.de>,
	Rui Santos <rsantos@...popie.com>,
	Michael B??ker <m.bueker@...lin.de>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] r8169: Reduce looping in the interrupt handler.

Eric W. Biederman <ebiederm@...ssion.com> :
[...]
> It is a bit weird but it also means we aren't playing silly games
> with status inside the loop.  So if we go through the loop we ack
> everything in status.

I fear we have some longstanding problem anyway :

1. quiescent state
2. packets are received
3. rtl8169_interrupt schedules napi, clears IntrStatus and exits
4. packets are received and some non-napi event happens
5. rtl8169_interrupt wakes up, reads IntrStatus and goes on...
6. rtl8169_poll wakes up, processes Rx and Tx napi events and goes on...
7. tp->intr_mask still equals ~tp->napi_event : rtl8169_interrupt
   handler does not even try to schedule napi.
8. more packets are received
9. rtl8169_interrupt clears IntrStatus
a. rtl8169_poll reenables napi scheduling, updates IntrMask and exits
b. rtl8169_interrupt reads a perfectly clean IntrStatus and exits

-- 
Ueimor
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