Date: Tue, 1 Feb 2011 15:18:03 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Stefan Lambrev <stefan.lambrev@moneybookers.com> Cc: freebsd-performance@freebsd.org, Julian Elischer <julian@freebsd.org>, Bruce Evans <brde@optusnet.com.au> Subject: Re: Interrupt performance Message-ID: <20110201121803.GT18170@zxy.spb.ru> In-Reply-To: <8979148D-8F2E-49E3-86EE-41CE6F57CDA4@moneybookers.com> References: <20110128143355.GD18170@zxy.spb.ru> <22E77EED-6455-4164-9115-BBD359EC8CA6@moneybookers.com> <20110128161035.GF18170@zxy.spb.ru> <CDBFAB7F-1EBC-4B3A-B2F5-6162DD58A93D@moneybookers.com> <4D42F87C.7020909@freebsd.org> <20110128172516.GG18170@zxy.spb.ru> <20110129070205.Q7034@besplex.bde.org> <20110201113724.GS18170@zxy.spb.ru> <8979148D-8F2E-49E3-86EE-41CE6F57CDA4@moneybookers.com>
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On Tue, Feb 01, 2011 at 02:07:51PM +0200, Stefan Lambrev wrote: > > I do some more test and build kernel with KTR. > > Now I don't think that inetrrupt overhead on FreeBSD weight: I try > > polling and don't see any difference. > > > > I see many reported by netperf send errors. I found this > > http://docs.freebsd.org/cgi/mid.cgi?E1Aice9-0002by-00. > > > > After insert into src/nettest_bsd.c usleep(1000) if ENOBUF I see 53% > > idle and ./loop 2000000000 "Elapsed 15188006 us" -- this near to linux > > (Elapsed 14107670 us). > > > > 10% of difference may be by more weight network stack (only 32104 > > ticks from 126136 in interrupt handler and task switching, and 94032 > > -- UDP processing in network stack and passing datagram to driver). > > May be weight SOCKBUF_LOCK/SOCKBUF_UNLOCK and/or > > INP_INFO_RUNLOCK/INP_RUNLOCK. > > Try to run with the same network buffers on FreeBSD and Linux. > I think, the default values in freebsd are much, much lower. Set large buffers on FreeBSD -- the first that I try. Also, netperf use setsockopt() and netperf run on linux with same options (include -s 128K -S 128K). > Also in the past ENOBUF was not handled properly in linux. > > http://wiki.freebsd.org/AvoidingLinuxisms - Do not rely on Linux-specific socket behaviour. In particular, default socket buffer sizes are different (call setsockopt() with SO_SNDBUF and SO_RCVBUF), and while Linux's send() blocks when the socket buffer is full, FreeBSD's will fail and set ENOBUFS in errno. Yes, about ENOBUFS with udp socket I told. And this behaviour (block on udp socket send) in Solaris too. I don't know what behaviour is right.
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