From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: 2.6.12 Performance problems Date: Wed, 24 Aug 2005 23:34:50 -0700 Message-ID: <430D668A.6030306@candelatech.com> References: <20050825060843.15874.qmail@web33311.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Jesper Juhl , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: To: danial_thom@yahoo.com In-Reply-To: <20050825060843.15874.qmail@web33311.mail.mud.yahoo.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Danial Thom wrote: > > --- Ben Greear wrote: > > >>Danial Thom wrote: >> >> >>>I think the concensus is that 2.6 has made >> >>trade >> >>>offs that lower raw throughput, which is what >> >>a >> >>>networking device needs. So as a router or >>>network appliance, 2.6 seems less suitable. A >> >>raw >> >>>bridging test on a 2.0Ghz operton system: >>> >>>FreeBSD 4.9: Drops no packets at 900K pps >>>Linux 2.4.24: Starts dropping packets at 350K >> >>pps >> >>>Linux 2.6.12: Starts dropping packets at 100K >> >>pps >> >>I ran some quick tests using kernel 2.6.11, 1ms >>tick (HZ=1000), SMP kernel. >>Hardware is P-IV 3.0Ghz + HT on a new >>SuperMicro motherboard with 64/133Mhz >>PCI-X bus. NIC is dual Intel pro/1000. Kernel >>is close to stock 2.6.11. >> >>I used brctl to create a bridge with the two >>GigE adapters in it and >>used pktgen to stream traffic through it >>(250kpps in one direction, 1kpps in >>the other.) >> >>I see a reasonable amount of drops at 250kpps >>(60 byte packets): >>about 60,000,000 packets received, 20,700 >>dropped. I get slightly worse performance on this system when running RH9 with kernel 2.4.29 (my hacks, HZ=1000, SMP). Tried increasing e1000 descriptors to 2048 tx and rx, but that didn't help, or at least not much. Will try some other tunings, but I doubt it will affect performance enough to come close to the discrepency that you show between 2.4 and 2.6 kernels... I tried copying a 500MB CDROM to HD on my RH9 system, and only 6kpps of the 250kpps get through the bridge...btw. Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com