From: Michael Cronenworth <mike@cchtml•com>
To: Alexander Duyck <alexander.h.duyck@redhat•com>,
intel-wired-lan@lists•osuosl.org, jeffrey.t.kirsher@intel•com
Cc: netdev@vger•kernel.org, htodd@twofifty•com
Subject: Re: [PATCH] e1000e: Cleanup handling of VLAN_HLEN as a part of max frame size
Date: Wed, 08 Apr 2015 23:48:51 -0500 [thread overview]
Message-ID: <552604B3.9070204@cchtml.com> (raw)
In-Reply-To: <20150408204630.4643.37880.stgit@ahduyck-vm-fedora22>
On 04/08/2015 04:02 PM, Alexander Duyck wrote:
> When the VLAN_HLEN was added to the calculation for the maximum frame size
> there seems to have been a number of issues added to the driver.
>
> The first issue is that in some cases the maximum frame size for a device
> never really reached the actual maximum frame size as the VLAN header
> length was not included the calculation for that value. As a result some
> parts only supported a maximum frame size of either 1496 in the case of
> parts that didn't support jumbo frames, and 8996 in the case of the parts
> that do.
>
> The second issue is the fact that there were several checks that weren't
> updated so as a result setting an MTU of 1500 was treated as enabling jumbo
> frames as the calculated value was 1522 instead of 1518. I have addressed
> those by replacing ETH_FRAME_LEN with VLAN_ETH_FRAME_LEN where appropriate.
>
> The final issue was the fact that lowering the MTU below 1500 would cause
> the driver to allocate 2K buffers for the rings. This is an old issue that
> was fixed several years ago in igb/ixgbe and I am addressing now by just
> replacing == with a <= so that we always just round up to 1522 for anything
> that isn't a jumbo frame.
Alex,
Thanks taking the time to work on a patch.
I have tested this patch in 4.0 on i218-v hardware and it is working. I see 9000 in
tcpdump (tso/gso off) and my switch blocks packets if I set the max frame size to
9017 down from 9018.
I also played with a VLAN real quick, and did not encounter any problems, but I
don't normally use VLANs so it may need further testing.
Thanks,
Michael
next prev parent reply other threads:[~2015-04-09 4:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-06 16:38 e1000e max frame calculation Michael Cronenworth
2015-04-06 18:38 ` Alexander Duyck
2015-04-06 21:45 ` Michael Cronenworth
2015-04-06 23:17 ` Alexander Duyck
2015-04-07 3:47 ` Hisashi T Fujinaka
2015-04-08 17:17 ` Alexander Duyck
2015-04-08 17:25 ` Hisashi T Fujinaka
2015-04-08 21:02 ` [PATCH] e1000e: Cleanup handling of VLAN_HLEN as a part of max frame size Alexander Duyck
2015-04-08 21:15 ` Hisashi T Fujinaka
2015-04-08 22:58 ` Alexander Duyck
2015-04-08 23:05 ` Hisashi T Fujinaka
2015-04-08 23:13 ` Alexander Duyck
2015-04-09 0:10 ` Hisashi T Fujinaka
2015-04-09 0:26 ` Hisashi T Fujinaka
2015-04-09 1:19 ` Alexander Duyck
2015-04-09 6:17 ` [Intel-wired-lan] " Templeman, Chaim
2015-04-09 15:51 ` Alexander Duyck
2015-04-13 18:26 ` Templeman, Chaim
2015-04-09 0:01 ` Jeff Kirsher
2015-04-09 4:48 ` Michael Cronenworth [this message]
2015-04-21 2:38 ` [Intel-wired-lan] " Brown, Aaron F
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