From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Gallatin Subject: Re: Receive side performance issue with multi-10-GigE and NUMA Date: Fri, 21 Aug 2009 11:36:00 -0400 Message-ID: <4A8EBEE0.6010901@myri.com> 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> <20090821152341.GA2998@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Bill Fink , Linux Network Developers , brice@myri.com To: Neil Horman Return-path: Received: from mailbox2.myri.com ([64.172.73.26]:1820 "EHLO myri.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932358AbZHUPgN (ORCPT ); Fri, 21 Aug 2009 11:36:13 -0400 In-Reply-To: <20090821152341.GA2998@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: Neil Horman wrote: > 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. Indeed. Another option when setting up a serial console is not practical is netconsole. I've captured a few panics this way on machines like macs, with no serial port support (at the time). Drew