* Re: Problem with Netpoll based netdumping and NAPI [not found] <20040419125148.GA4495@in.ibm.com> @ 2004-04-19 17:42 ` Matt Mackall 2004-04-21 6:00 ` Hariprasad Nellitheertha 0 siblings, 1 reply; 2+ messages in thread From: Matt Mackall @ 2004-04-19 17:42 UTC (permalink / raw) To: Hariprasad Nellitheertha; +Cc: netdev, linux-kernel, mingo, suparna [changed cc: from linux-net to netdev] On Mon, Apr 19, 2004 at 06:21:48PM +0530, Hariprasad Nellitheertha wrote: > Hi All, > > I am facing a problem while trying to network dump using LKCD. My > debugging so far indicates that this is due to both NAPI and NETPOLL > being enabled. > > I am using LKCD on the 2.6.5 kernel and both the client and server are > i386 boxes. The dumping machine has an e100 card. I have built the kernel > with both CONFIG_E100_NAPI and CONFIG_NET_POLL_CONTROLLER (and the other > netpoll related options) selected. > > LKCD uses netpoll for its network dump implementation. The problem we see > is that the network dump driver does not receive any packet from the > card driver and hence dumping fails. In e100_intr(), we call > netif_rx_schedule() if we are using the NAPI feature. netif_rx_schedule, > in turn, ends up adding the processing of this packet to the NET_RX_SOFTIRQ > softirq. Netpoll should be manually calling the NAPI poll function like this after calling the interrupt handler (in netpoll_poll()): /* If scheduling is stopped, tickle NAPI bits */ if(trapped && np->dev->poll && test_bit(__LINK_STATE_RX_SCHED, &np->dev->state)) np->dev->poll(np->dev, &budget); Please ensure that LKCD is calling netpoll_set_trap(1) which tells it that packet scheduling is stopped. I've tested this path primarily with tg3 and kgdb-over-ethernet, but it should be functionally quite similar to e100 and lkcd. -- Matt Mackall : http://www.selenic.com : Linux development and consulting ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Problem with Netpoll based netdumping and NAPI 2004-04-19 17:42 ` Problem with Netpoll based netdumping and NAPI Matt Mackall @ 2004-04-21 6:00 ` Hariprasad Nellitheertha 0 siblings, 0 replies; 2+ messages in thread From: Hariprasad Nellitheertha @ 2004-04-21 6:00 UTC (permalink / raw) To: Matt Mackall; +Cc: netdev, linux-kernel, mingo, suparna Hi Matt, On Mon, Apr 19, 2004 at 12:42:54PM -0500, Matt Mackall wrote: > [changed cc: from linux-net to netdev] > > On Mon, Apr 19, 2004 at 06:21:48PM +0530, Hariprasad Nellitheertha wrote: > > Hi All, > > > > I am facing a problem while trying to network dump using LKCD. My > > debugging so far indicates that this is due to both NAPI and NETPOLL > > being enabled. > > > > I am using LKCD on the 2.6.5 kernel and both the client and server are > > i386 boxes. The dumping machine has an e100 card. I have built the kernel > > with both CONFIG_E100_NAPI and CONFIG_NET_POLL_CONTROLLER (and the other > > netpoll related options) selected. > > > > LKCD uses netpoll for its network dump implementation. The problem we see > > is that the network dump driver does not receive any packet from the > > card driver and hence dumping fails. In e100_intr(), we call > > netif_rx_schedule() if we are using the NAPI feature. netif_rx_schedule, > > in turn, ends up adding the processing of this packet to the NET_RX_SOFTIRQ > > softirq. > > Netpoll should be manually calling the NAPI poll function like this > after calling the interrupt handler (in netpoll_poll()): > > /* If scheduling is stopped, tickle NAPI bits */ > if(trapped && np->dev->poll && > test_bit(__LINK_STATE_RX_SCHED, &np->dev->state)) > np->dev->poll(np->dev, &budget); > > Please ensure that LKCD is calling netpoll_set_trap(1) which tells it > that packet scheduling is stopped. This was indeed the problem. We were not calling netpoll_set_trap in LKCD. Adding this fixed the problem. Thanks so much for your help with this. Regards, Hari > > I've tested this path primarily with tg3 and kgdb-over-ethernet, but > it should be functionally quite similar to e100 and lkcd. > > -- > Matt Mackall : http://www.selenic.com : Linux development and consulting -- Hariprasad Nellitheertha Linux Technology Center India Software Labs IBM India, Bangalore ^ permalink raw reply [flat|nested] 2+ messages in thread
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2004-04-19 17:42 ` Problem with Netpoll based netdumping and NAPI Matt Mackall
2004-04-21 6:00 ` Hariprasad Nellitheertha
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