Date: Tue, 6 Oct 2009 11:34:08 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: rihad <rihad@mail.ru> Cc: freebsd-net@freebsd.org, Julian Elischer <julian@elischer.org> Subject: Re: dummynet dropping too many packets Message-ID: <20091006093408.GA86830@onelab2.iet.unipi.it> In-Reply-To: <4ACB0C22.4000008@mail.ru> References: <4AC9CFF7.3090208@mail.ru> <20091005110726.GA62598@onelab2.iet.unipi.it> <4AC9D87E.7000005@mail.ru> <20091005120418.GA63131@onelab2.iet.unipi.it> <4AC9E29B.6080908@mail.ru> <20091005123230.GA64167@onelab2.iet.unipi.it> <4AC9EFDF.4080302@mail.ru> <4ACA2CC6.70201@elischer.org> <4ACAFF2A.1000206@mail.ru> <4ACB0C22.4000008@mail.ru>
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On Tue, Oct 06, 2009 at 02:21:38PM +0500, rihad wrote: > rihad wrote: > >Julian Elischer wrote: > >>rihad wrote: > >>>Luigi Rizzo wrote: > >>>>2. your test with 'ipfw allow ip from any to any' does not > >>>> prove that the interface queue is not saturating, because > >>>> you also remove the burstiness that dummynet introduces, > >>>> and so the queue is driven differently. > >>>> > >>> > >>>How do I investigate and fix this burstiness issue? > >> > >>higher Hz rate? > >> > > > >Rebooted with HZ=2000 10 minutes ago. Due to application design the ipfw > > table (pipe tablearg) was flushed, so there are now 350 (and increasing > >at a rate 1 per 1-2 seconds as I type this) or so users in the table, > >and not 4k as normally would be. The box is servicing 450+ mbit/s > >without a single drop. I want to monitor how things change once the > >number of users in ipfw tables gradually increases up to several thousands. > > > > It starts dropping packets at around 2000 online users (ipfw table > load). I've set up a shell script to monitor this: once again: you should check which pipes are dropping packets and whether the number of drops indicated in the pipes matches the counts indicated by netstat. cheers luigi > # while :; do ipfw table 0 list | wc -l; netstat -s 2>/dev/null |fgrep > -w 'output packets dropped'; sleep 10; done > > ... # all zeroes above this > 1999 > 0 output packets dropped due to no bufs, etc. > 2001 > 0 output packets dropped due to no bufs, etc. > 2008 > 0 output packets dropped due to no bufs, etc. > 2017 > 0 output packets dropped due to no bufs, etc. > 2027 > 156 output packets dropped due to no bufs, etc. > 2037 > 156 output packets dropped due to no bufs, etc. > 2045 > 156 output packets dropped due to no bufs, etc. > 2372 > 202 output packets dropped due to no bufs, etc. > 2377 > 207 output packets dropped due to no bufs, etc. > 2391 > 338 output packets dropped due to no bufs, etc. > 2402 > 394 output packets dropped due to no bufs, etc. > 2415 > 531 output packets dropped due to no bufs, etc. > 2421 > 725 output packets dropped due to no bufs, etc. > > > Is there some limit on the number of IP addresses in an ipfw table? > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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