From owner-freebsd-net@freebsd.org  Sat Sep 22 20:52:45 2018
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Date: Sat, 22 Sep 2018 23:52:07 +0300
From: Lev Serebryakov <lev@FreeBSD.org>
Reply-To: Lev Serebryakov <lev@FreeBSD.org>
Organization: FreeBSD
Message-ID: <1377072414.20180922235207@serebryakov.spb.ru>
To: net@FreeBSD.org
CC: sbruno@FreeBSD.org, marius@FreeBSD.org
Subject: Looks like igb on 12-ALPHA6 (driver 7.6.1-k) and on 11-STABLE (driver
 2.5.3-k) behave very differently on receive [regression?]
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Hello Net,

  I have two systems with almost identical NICs: one with igb, chip=0x15338086, with FreeBSD
11-STABLE and other with igb, chip=0x157b8086 and FreeBSD 12-ALPHA6
installed.

 All options are turned ON, mtu=9000 on both ends.

 When I send single TCP stream from 12-ALPHA6 to 11-STABLE I get 990MBit/s.

 When I send single TCP stream from 11-STABLE to 12-ALPHA6 I get only
710Mbit/s.

 I've sniffed traffic on both systems and I could see, that 11-STABLE driver
assemble incoming (9014 bytes) packets to large chunks. Typical "captured
frame size" is 45KB, about 5 Jumbo frames. But 12-ALPHA6 driver apss "small"
packets to the system: maximum size is 17KB and there are lot of 9014 bytes
frames.

 Unfortunately, driver versions are so much different that I can not compare
"sysctl dev.igb.0" in any meaningful way.

 Yes, I know, that CPUs on these systems are very different, but looks like
it is driver regression.

 Any hints?

-- 
Best regards,
 Lev                          mailto:lev@FreeBSD.org