From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: dev@dpdk.org, maxime.coquelin@redhat.com, huawei.xie@intel.com,
stephen@networkplumber.org, "Tan,
Jianfeng" <jianfeng.tan@intel.com>,
Tomasz Kulasek <tomaszx.kulasek@intel.com>,
Thomas Monjalon <thomas.monjalon@6wind.com>,
Konstantin Ananyev <konstantin.ananyev@intel.com>
Subject: Re: [dpdk-dev] [PATCH 5/5] net/virtio: fix Tso when mbuf is shared
Date: Wed, 18 Jan 2017 13:03:48 +0800 [thread overview]
Message-ID: <20170118050348.GO10293@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <20170117121825.3db48369@platinum>
On Tue, Jan 17, 2017 at 12:18:25PM +0100, Olivier Matz wrote:
> > I hope I could have time to dig this further, since, honestly, I don't
> > quite like this patch: it makes things un-maintainable.
>
> Well, I'm not that proud of the patch, but that's the best solution
> I've found. Nevertheless saying it makes things un-maintainable looks a
> bit excessive to me :)
Aha... really sorry about that!
But honestly, I'd say again, it makes thing more complex, just for fixing
a corner and rare issue. I'd try to avoid that.
>
> The option of reallocating a mbuf, copy and fix network headers in it
> looks even more complex to me (that was my first approach).
>
> > Besides that, I think we have similar issue with nic drivers. See the
> > rte_net_intel_cksum_flags_prepare() function introduced at commit
> > 4fb7e803eb1a ("ethdev: add Tx preparation").
>
> Yes, that was discussed a bit. See [1] and the subsequent mails.
> http://dpdk.org/ml/archives/dev/2016-December/051014.html
Thanks for the info, and I'm pretty Okay with that.
> My opinion is that tx_burst() should not change the mbuf data, it's
> always been like this. For Intel NICs, there is no issue since the DPDK
> API is derived from Intel NICs API, so there is no fix to do in the
> mbuf data.
>
> For tx_prepare(), it's explicitly said that it can update the data.
> If tx_prepare() becomes mandatory, it will naturally fix this issue
> without modifying the driver, because the phdr csum calculation will be
> done in tx_prepare().
>
> An alternative is to mark this as a known issue for now, and wait until
> tx_prepare() is mandatory.
I see no reason to wait. Though my understanding is it may not be a
mandatory so far, but user is supposed to calculate the pseudo-header
checksum by themself before. Now they have one more option: tx_prepare.
That means, in either way, user has to do some extra works to make
TSO work (either by themself or call tx_prepare). So I don't think
it'd be an issue?
--yliu
next prev parent reply other threads:[~2017-01-18 5:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-24 8:56 [dpdk-dev] [PATCH 0/5] virtio/mbuf: fix virtio tso with shared mbufs Olivier Matz
2016-11-24 8:56 ` [dpdk-dev] [PATCH 1/5] mbuf: remove const attribute in mbuf read function Olivier Matz
2016-11-24 8:56 ` [dpdk-dev] [PATCH 2/5] mbuf: new helper to check if a mbuf is shared Olivier Matz
2016-11-24 8:56 ` [dpdk-dev] [PATCH 3/5] mbuf: new helper to write data in a mbuf chain Olivier Matz
2016-11-24 8:56 ` [dpdk-dev] [PATCH 4/5] mbuf: new helper to copy data from a mbuf Olivier Matz
2016-11-24 8:56 ` [dpdk-dev] [PATCH 5/5] net/virtio: fix Tso when mbuf is shared Olivier Matz
2016-12-14 7:27 ` Yuanhan Liu
2017-01-09 17:46 ` Olivier Matz
2017-01-16 6:48 ` Yuanhan Liu
2017-01-17 11:18 ` Olivier Matz
2017-01-18 5:03 ` Yuanhan Liu [this message]
2017-01-24 10:51 ` Olivier MATZ
2017-01-28 12:32 ` Yuanhan Liu
2017-01-09 17:59 ` Stephen Hemminger
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