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Date: Fri, 06 Apr 2007 17:08:28 +0200 From: Patrick McHardy <kaber@...sh.net> To: Vasily Averin <vvs@...ru> CC: Eric Dumazet <dada1@...mosbay.com>, "David S. Miller" <davem@...emloft.net>, Andrew Morton <akpm@...ux-foundation.org>, netfilter-devel@...ts.netfilter.org, rusty@...tcorp.com.au, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, devel@...nvz.org Subject: Re: [PATCH 2.6.21-rc6] [netfilter] early_drop imrovement Vasily Averin wrote: > No, I've not investigated this scenario. It looks like you are right and my > patch can leads to a long delays. > > In my experiments I've decreased ip_conntrack_max lower than number of hash > buckets and got the "table full, dropping packet" errors in logs. I've looked on > the conntrack list and found a huge number of conntracks that can be freed. > However my hash bucket was empty and therefore I even did not have any chances > to free something. That's why I would like to check the other hash buckets too. > > Ok, let's limit the number of conntracks that can be checked inside > early_drop(). What do you prefer: some round number (for example 100) or > fraction of ip_conntrack_max (for example 1%)? A (small) fraction sounds better. We could even consider keeping track of the number of conntracks that can be evicted (not assured), so in a DOS situation we could save unnecessary table scans. Not sure if its worth the effort though. Anyway, please base your patch on the net-2.6.22 tree, which doesn't include ip_conntrack anymore. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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