1<!doctype linuxdoc system> 2 3<article> 4 5<title>RTACCT Utility 6<author>Robert Olsson 7<date>some_negative_number, 20 Dec 2001 8 9<p> 10Here is some code for monitoring the route cache. For systems handling high 11network load, servers, routers, firewalls etc the route cache and its garbage 12collection is crucial. Linux has a solid implementation. 13 14<p> 15The kernel patch (not required since linux-2.4.7) adds statistics counters 16from route cache process into 17/proc/net/rt_cache_stat. A companion user mode program presents the statistics 18in a vmstat or iostat manner. The ratio between cache hits and misses gives 19the flow length. 20 21<p> 22Hopefully it can help understanding performance and DoS and other related 23issues. 24 25<p> An URL where newer versions of this utility can be (probably) found 26is ftp://robur.slu.se/pub/Linux/net-development/rt_cache_stat/ 27 28 29<p><bf/Description/ 30 31<p>The format of the command is: 32 33<tscreen><verb> 34 rtstat [ OPTIONS ] 35</verb></tscreen> 36 37<p> <tt/OPTIONS/ are: 38 39<itemize> 40 41<item><tt/-h/, <tt/-help/ - show help page and version of the utility. 42 43<item><tt/-i INTERVAL/ - interval between snapshots, default value is 442 seconds. 45 46<item><tt/-s NUMBER/ - whether to print header line. 0 inhibits header line, 471 prescribes to print it once and 2 (this is default setting) forces header 48line each 20 lines. 49 50</itemize> 51 52</article> 53