On Mon, Aug 07, 2006 at 11:40:49AM -0400, jamal wrote:
>
> On Mon, 2006-07-08 at 17:21 +0200, Edgar E. Iglesias wrote:
> [..]
> > I have a question regarding your patch. In clean_tx_irq, it seems you dont
> > clean the ring unless fdesc < tx_ring->prunet. Won't this cause deadlocks
> > for
> > local TCP connections if transmit goes quiet?
> >
>
> I have not tested the TCP case; however, note that the specific part you
> reference is commented out. There are no deadlock issues in the case of
> forwarding (as in my testcases).
Ok, I thought you wanted the code inside the ifdefs to be considered. If not,
I guess there is no problem. Yes, the forwarding case does not suffer from
any deadlocks issues that I am aware of.
>
> I did not quiet follow the ensuing discussion after your post:
> These descriptors being pruned in the tx path happen only after the
> packets have been sent out on the wire. Why would this contribute to a
> deadlock but not when it happens on the receive path? It is true that
> tcp retransmit queue will still be referencing the skbs, but why is it
> any different because in one case it happens in the tx and in the other
> on the receive? Is there dependency on waking up the queue?
No, the deadlock happens only if you don't prune the descriptors. If the host
sends some data and then goes quite, fdesc < tx_ring->prunet might not be
true for a long time and skbs will end up sitting in the tx ring indefinitely,
charging the socket's sndbuf.
Best regards
--
Programmer
Edgar E. Iglesias <[EMAIL PROTECTED]> 46.46.272.1946
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