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Date: Wed, 08 Jan 2014 15:13:46 -0800 From: Eric Dumazet <eric.dumazet@...il.com> To: Christoph Paasch <christoph.paasch@...ouvain.be> Cc: netdev@...r.kernel.org, David Miller <davem@...emloft.net>, Yuchung Cheng <ycheng@...gle.com>, Julian Anastasov <ja@....bg> Subject: Re: [PATCH net-next v2 2/5] tcp: metrics: Add source-address to tcp-metrics On Wed, 2014-01-08 at 23:43 +0100, Christoph Paasch wrote: > Hello Eric, > > On 08/01/14 - 09:55:51, Eric Dumazet wrote: > > On Wed, 2014-01-08 at 16:05 +0100, Christoph Paasch wrote: > > > We add the source-address to the tcp-metrics, so that different metrics > > > will be used per source/destination-pair. We use the destination-hash to > > > store the metric inside the hash-table. That way, deleting and dumping > > > via "ip tcp_metrics" is easy. > > > > Note that this has the following problem : > > > > Some applications use a set of source IP addresses to overcome the 64K > > port limitation. > > Ok, did not know about that. > > > tcp_metrics uses a hard-coded TCP_METRICS_RECLAIM_DEPTH value of 5, > > meaning that cache wont be able to store more than 5 source IP addresses > > (reaching one particular remote IP). > > Maybe we could do something like the below (yet untested). That way we allow > up to 32 entries with the same destination but different source and still > only 5 with different destinations. > > I guess 32 * 64K connections is enough. :) > We could also make TCP_METRICS_RECLAIM_DEPTH(_DST) a tunable. Well, not sure if this is a problem anyway, and if we want extra complexity for this rare use case, considering tcp metrics for high number of flows sharing a common path is unlikely to be useful (with exception of Fast Open, but again it must be rare) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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