From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: Re: Receive side performance issue with multi-10-GigE and NUMA Date: Fri, 21 Aug 2009 11:23:41 -0400 Message-ID: <20090821152341.GA2998@localhost.localdomain> References: <20090807170600.9a2eff2e.billfink@mindspring.com> <20090807221211.GA16874@localhost.localdomain> <20090807205442.32918186.billfink@mindspring.com> <20090808015612.GA17710@localhost.localdomain> <20090814164412.be5daa74.billfink@mindspring.com> <20090814232543.GA28599@hmsreliant.think-freely.org> <20090820035044.9b70fca6.billfink@mindspring.com> <20090820201919.GA20750@localhost.localdomain> <20090821001421.214a560b.billfink@mindspring.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linux Network Developers , brice@myri.com, gallatin@myri.com To: Bill Fink Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:52539 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754753AbZHUPXx (ORCPT ); Fri, 21 Aug 2009 11:23:53 -0400 Content-Disposition: inline In-Reply-To: <20090821001421.214a560b.billfink@mindspring.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Aug 21, 2009 at 12:14:21AM -0400, Bill Fink wrote: > On Thu, 20 Aug 2009, Neil Horman wrote: > > > On Thu, Aug 20, 2009 at 03:50:44AM -0400, Bill Fink wrote: > > > > > When I tried an actual nuttcp performance test, even when rate limiting > > > to just 1 Mbps, I immediately got a kernel oops. I tried to get a > > > crashdump via kexec/kdump, but the kexec kernel, instead of just > > > generating a crashdump, fully booted the new kernel, which was > > > extremely sluggish until I rebooted it through a BIOS re-init, > > > and never produced a crashdump. I tried this several times and > > > an immediate kernel oops was always the result (with either a TCP > > > or UDP test). A ping test of 1000 9000-byte packets with an interval > > > of 0.001 seconds (which is 72 Mbps for 1 second) on the other hand > > > worked just fine. > > > > The sluggishness is expected, since the kdump kernel operates out of such > > limited memory. don't know why you booted to a full system rather than did a > > crash recovery. Don't suppose you got a backtrace did you? > > There was a backtrace on the screen but I didn't have a chance to > record it. BTW did anyone ever think to print the backtrace in > reverse (first to some reserved memory and then output to the display) > so the more interesting parts wouldn't have scrolled off the top of > the screen? > The real solution is to use a console to which the output doesn't scroll off the screen. Normally people use a serial console they can log, or a RAC card that they can record. Even on a regular vga monitor in text mode, you can set up the vt iirc to allow for scrolling. Neil > -Bill >