Re: Longstanding networking / SMP issue? (duplextest)

David S. Miller (davem@redhat.com)
Fri, 21 Feb 2003 01:43:16 -0800 (PST)


From: Andi Kleen <ak@suse.de>
Date: Fri, 21 Feb 2003 08:27:19 +0100

For icmp_xmit_lock it can be only done in a limited fashion - you are
always restricted by the buffer size of the ICMP socket. Also I don't
know how to lock the socket from BH context nicely - the only simple way
probably is the trick from the retransmit timer to just try again
in a jiffie, but could have nasty queueing up under high load.

Fixing the error drop behaviour of TCP will be somewhat nasty too.

In both cases you'll need a retry timer (unreliable) or an dedicated ICMP
backlog (complicated)

The big problem is that we have one ICMP socket for UP and only
one for SMP too. That's just dumb, we should make this be a
per-cpu thing.

I suspect this will fix the original bug report.

I don't think the TCP case is much of an issue. TCP retries things
etc.
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