netdev - Re: pktgen and spin_lock

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Message-ID: <4ADE44FC.4030406@candelatech.com>
Date:	Tue, 20 Oct 2009 16:17:16 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	NetDev <netdev@...r.kernel.org>, robert@...julf.net,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: pktgen and spin_lock_bh in xmit path

On 10/20/2009 02:57 PM, Eric Dumazet wrote:
> Ben Greear a écrit :
>> That's definitely a nasty little issue.  Using skb_set_queue_mapping
>> in pktgen makes it run for me, but may just be getting lucky with the
>> mac-vlan interfaces which will do the dev_queue_xmit (but, I don't so much
>> care exactly what queue is used as long as things don't crash and the
>> link doesn't reset).
>>
>> Don't worry about a quick patch on my account.  I seem to have it working
>> to at least some degree (no funny crashes, no link watchdog timeouts).
>>
>
> Could you try following patch ?
>
> This makes queue_mapping invariant if set in range [0 ... real_num_tx_queues-1]

Yes, that runs w/out causing link resets and without crashes (just tested it for
a few minutes).

Interestingly, the pkts sent by pktgen on the mac-vlans end up in
tx-queues that match processor ID, even though I'm on .31 where mac-vlans
have only one tx-queue and pktgen is setting the queue to 0 in the skb
(per your previous patch).

Must be something somewhere doing the mapping of processor ids to txqs.

I'll try to figure this out this evening or tomorrow.

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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