On 2016/11/02 21:19, Brown, Aaron F wrote: > > From: Jack Suter [mailto:j...@suter.io] > > Sent: Tuesday, November 1, 2016 4:57 PM > > To: Kirsher, Jeffrey T <jeffrey.t.kirs...@intel.com> > > Cc: intel-wired-...@lists.osuosl.org; bpoir...@suse.com; Brown, Aaron F > > <aaron.f.br...@intel.com>; jhod...@ucdavis.edu; linux- > > ker...@vger.kernel.org > > Subject: Kernel regression introduced by "e1000e: Do not write lsc to ics in > > msi-x mode" and/or "e1000e: Do not read ICR in Other interrupt" > > > > Hi there, > > > > I have some servers with an 82574L based NIC and recently upgraded from > > a 4.4 series kernel to 4.7. Upon doing so, servers with this chipset > > have begun frequently reporting "Link is Down" and "Link is Up" > > messages. No other related network errors are reported by the kernel or > > e1000e driver. I saw some reports about using "ethtool -s $iface msglvl > > 6" to reveal more information, but nothing extra was reported. > > > > Some testing showed that this was introduced between the 4.4 and 4.5 > > series. I was able to further narrow it down to two commits that look > > related: > > > > e1000e: Do not write lsc to ics in msi-x mode > > (a61cfe4ffad7864a07e0c74969ca7ceb77ab2f1f) > > e1000e: Do not read ICR in Other interrupt > > (16ecba59bc333d6282ee057fb02339f77a880beb) > > I did not notice any link flapping when I tested those patches, I would have > rejected them if I had. I have several systems with 82574L LOMs and as yet > am not able to reproduce a link flap with recent upstream kernels/drivers > (net-next 4.8.0 on one and 4.9.0-rc3 on another.) > > One of those systems is dedicated to a kernel regression setup, I checked the > test logs from it and am not seeing any evidence of flaps in the 4.4, through > 4.6 range either. > > > > > Reverting these two commits resolves the Link is Down/Link is Up > > messages. This has been tested on about six servers so far and all have > > stopped reporting these link flaps. > > Are you able to revert either of the patches independently, I don't recall if > they were stand alone or not.
>From what I recall, the series is entirely bisectable. I tested again just now and could do a netperf RR test after applying each commit sequentially.
