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Re: [BUG] overflow in net/ipv4/route.c rt_check_expire()

To: Robert Olsson <Robert.Olsson@xxxxxxxxxxx>
Subject: Re: [BUG] overflow in net/ipv4/route.c rt_check_expire()
From: Eric Dumazet <dada1@xxxxxxxxxxxxx>
Date: Sat, 02 Apr 2005 16:10:10 +0200
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>, davem@xxxxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <16974.41648.568927.54429@robur.slu.se>
References: <E1DHdsP-0003Lr-00@gondolin.me.apana.org.au> <424E641A.1020609@cosmosbay.com> <16974.41648.568927.54429@robur.slu.se>
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Robert Olsson a écrit :
Eric Dumazet writes:

Yes thats a pretty much load. Very short flows some reason?

Well... yes. This is a real server, not a DOS simulation. 1 million TCP flows, and about 3 million peers using UDP frames.

What's your ip_rt_gc_min_interval? GC should be allowed to run frequent to smoothen out the GC load. Also good idea to decrease gc_thresh and you hash is really huge.

No. As soon as I lower gc_thresh (and let gc running), the machine starts to drop connections and crash some seconds later. I found I had to make the hash table very large (but lowering elasticity, ie chain length) . It needs lot of ram, but at least CPU usage of net/ipv4/route.c is close to 0.

# grep . /proc/sys/net/ipv4/route/*
/proc/sys/net/ipv4/route/error_burst:5000
/proc/sys/net/ipv4/route/error_cost:1000
/proc/sys/net/ipv4/route/gc_elasticity:2
/proc/sys/net/ipv4/route/gc_interval:1
/proc/sys/net/ipv4/route/gc_min_interval:0
/proc/sys/net/ipv4/route/gc_min_interval_ms:500
/proc/sys/net/ipv4/route/gc_thresh:2900000
/proc/sys/net/ipv4/route/gc_timeout:155
/proc/sys/net/ipv4/route/max_delay:10
/proc/sys/net/ipv4/route/max_size:16777216
/proc/sys/net/ipv4/route/min_adv_mss:256
/proc/sys/net/ipv4/route/min_delay:2
/proc/sys/net/ipv4/route/min_pmtu:552
/proc/sys/net/ipv4/route/mtu_expires:600
/proc/sys/net/ipv4/route/redirect_load:20
/proc/sys/net/ipv4/route/redirect_number:9
/proc/sys/net/ipv4/route/redirect_silence:20480
/proc/sys/net/ipv4/route/secret_interval:36000


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