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Date: Tue, 26 Jun 2012 01:37:30 -0700 (PDT) From: David Miller <davem@...emloft.net> To: eric.dumazet@...il.com Cc: netdev@...r.kernel.org Subject: Re: [PATCH] ipv4: Remove unnecessary code from rt_check_expire(). From: Eric Dumazet <eric.dumazet@...il.com> Date: Tue, 26 Jun 2012 10:23:04 +0200 > Thats because gc_interval (60) is big compared to ip_rt_gc_timeout > (300) > > So each time rt_check_expire() triggers, we handle a big part of the > cache. On big servers I had to lower gc_interval to smooth things. I know it's stupid, that's why I want to eventually kill this off completely. > Garbage collect is needed to not waste kernel memory, even on legitimate > traffic on a typical web server. > > Taken from my 8GB machine : > > # cat /proc/sys/net/ipv4/route/gc_thresh > 262144 > > 320 bytes per dst : 262144*320 = 83886080 bytes to store one dst per hash chain. 83MB on a machine with 8GB of ram that does enough networking to fill the routing cache. This sounds absolutely reasonable to me. > Also, why keeping a dst in cache if no traffic uses it in a 5 minutes period ? Traffic is bursty and periodic. And think, we don't do any stupidity like this for the inetpeer cache and no small cute animals have died as a result. -- 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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