netdev - Re: 2.6.29 forcedeth hang W/O NAPI enabled

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Date:	Thu, 26 Mar 2009 16:29:24 -0700 (PDT)
From:	Adam Richter <adam_richter2004@...oo.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	davem@...emloft.net, netdev@...r.kernel.org, berkley@...wustl.edu
Subject: Re: 2.6.29 forcedeth hang W/O NAPI enabled


On Wed, 3/25/09, Herbert Xu <herbert@...dor.apana.org.au> wrote:
> Thanks for testing! Since you also have a forcedeth card,
> could
> you try rebuilding your kernel with FORCEDETH_NAPI enabled
> and
> see if that is stable?

It works so far, doing "ping -f" for more than five minutes while I
browse the web, but bear in mind that I was not able to reproduce the
problem earlier with FORCEDETH_NAPI on demand.  I only saw an ethernet lock up with NAPI enabled once (with the original 2.6.29 code).  I
will let you know if the lockup occurs with your code. 

Just to be clear which version I am now testing, I have attached a
copy of process_backlog() from my net/core/dev.c.

Adam



static int process_backlog(struct napi_struct *napi, int quota)
{
	int work = 0;
	struct softnet_data *queue = &__get_cpu_var(softnet_data);
	unsigned long start_time = jiffies;

	napi->weight = weight_p;
	do {
		struct sk_buff *skb;

		local_irq_disable();
		skb = __skb_dequeue(&queue->input_pkt_queue);
		if (!skb) {
			list_del(&napi->poll_list);
			clear_bit(NAPI_STATE_SCHED, &napi->state);
			local_irq_enable();
			break;
		}
		local_irq_enable();

		napi_gro_receive(napi, skb);
	} while (++work < quota && jiffies == start_time);

	napi_gro_flush(napi);

	return work;
}



      
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