From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Cochran Subject: Re: Kernel 4.6.7-rt13: Intel Ethernet driver igb causes huge latencies in cyclictest Date: Mon, 17 Oct 2016 21:03:34 +0200 Message-ID: <20161017190334.GA19627@netboy> References: <13c3cd3ffee4490fb22b8de383e51361@FE-MBX1012.de.bosch.com> <29250f87b1d84aacb8aa312935582291@FE-MBX1012.de.bosch.com> <20161010193958.GE22235@jcartwri.amer.corp.natinst.com> <20161013161839.GV10625@jcartwri.amer.corp.natinst.com> <20161014220633.GA1811@netboy> <20161017183645.GA9435@jcartwri.amer.corp.natinst.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Koehrer Mathias (ETAS/ESW5)" , "Williams, Mitch A" , "Kirsher, Jeffrey T" , "linux-rt-users@vger.kernel.org" , Sebastian Andrzej Siewior , "netdev@vger.kernel.org" , "intel-wired-lan@lists.osuosl.org" , Greg To: Julia Cartwright Return-path: Content-Disposition: inline In-Reply-To: <20161017183645.GA9435@jcartwri.amer.corp.natinst.com> Sender: netdev-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On Mon, Oct 17, 2016 at 01:36:45PM -0500, Julia Cartwright wrote: > While that is certainly the case, and would explain the most egregious > of measured latency spikes, it doesn't invalidate the test if you > consider the valuable data point(s) to be the minimum and/or median > latencies. Well, consider the case where an interrupt is stuck on. That is a possible cause, and it can be positively excluded by either disabling local interrupts around the time stamps or by putting the vector events into the trace. (Doesn't matter now that bisection fingered the PCIe setup, just sayin.) Thanks, Richard