From: "Grumbach, Emmanuel" <emmanuel.grumbach-ral2JQCrhuEAvxtiuMwx3w@public•gmane.org>
To: Eric Dumazet <eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org>
Cc: "linux-wireless-u79uwXL29TY76Z2rM5mHXA@public•gmane.org"
<linux-wireless-u79uwXL29TY76Z2rM5mHXA@public•gmane.org>,
"ido-Ix1uc/W3ht7QT0dZR+AlfA@public•gmane.org"
<ido-Ix1uc/W3ht7QT0dZR+AlfA@public•gmane.org>,
"netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org"
<netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org>
Subject: Re: [RFC v2 0/3] add TSO / A-MSDU TX for iwlwifi
Date: Wed, 19 Aug 2015 17:56:20 +0000 [thread overview]
Message-ID: <0BA3FCBA62E2DC44AF3030971E174FB32E825252@hasmsx107.ger.corp.intel.com> (raw)
In-Reply-To: 1440004777.6610.23.camel@edumazet-glaptop2.roam.corp.google.com
On 08/19/2015 08:20 PM, Eric Dumazet wrote:
> On Wed, 2015-08-19 at 17:00 +0000, Grumbach, Emmanuel wrote:
>>
>> On 08/19/2015 07:08 PM, Eric Dumazet wrote:
>>> On Wed, 2015-08-19 at 15:07 +0000, Grumbach, Emmanuel wrote:
>>>
>>>> I'll look at it.
>>>> I was almost starting to implement that but then I thought with another
>>>> (good?) reason to use LSO. LSO gives me the guarantee that the packet is
>>>> directed to one peer, which might not be the case with xmit_more since
>>>> we have one Qdisc for several clients in case we are in AP mode.
>>>> Building an A-MSDU for several clients is not possible, at least not for
>>>> several client in the L2 (different MAC addresses).
>>>> LSO avoids this problem completely.
>>>
>>> Then, simply calling skb_gso_segment() from the driver might be enough,
>>> and less work for you.
>>>
>>> This would even support TSO on IPv6
>>>
>>
>> Well... I did take care of IPv6.
>
> net/core/tso.c does not yet handle IPv6
>
Yeah - I can see that now.
I can teach him - that's not a big deal. The bigger problem is that
net/core/tso.c doesn't do what I really need: it does only a small
portion. Since I need to add one frag to several skbs, I need to
refcount the frags' page. net/core/tso.c hides the page from me.
I can try to use tso_build_hdr but it will copy the entire header where
I need only SNAP / IP / TCP (and not 802.11).
I am getting the feeling that net/core/tso.c is close to what I need,
but not close enough to be usable without making changes that would make
the implementation too complicated and changing net/core/tso.c in a way
that would be much less readable for other users.
I know that our device is quite "unique" in the sense that most other
vendors do all the header twiddling in hardware. We unfortunately don't.
The A-MSDU's format is also somewhat unusual:
<802.11 HDR>
<ETH><SNAP><IP><TCP><PAYLOAD><PAD (variable length)
<ETH><SNAP><IP><TCP><PAYLOAD><PAD (variable length)
<ETH><SNAP><IP><TCP><PAYLOAD><PAD (variable length)
etc...
So I feel that making net/core/tso.c more complicated just because of
our craziness seems an overkill to me.
I'll try a bit harder to see how I can use net/core/tso.c, but I have to
say I am pessimistic.
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public•gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2015-08-19 17:56 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-19 12:59 [RFC v2 0/3] add TSO / A-MSDU TX for iwlwifi Emmanuel Grumbach
2015-08-19 12:59 ` [RFC v2 1/3] iwlwifi: mvm: add real TSO implementation Emmanuel Grumbach
[not found] ` <1439989181-4444-2-git-send-email-emmanuel.grumbach-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2015-08-19 14:17 ` Eric Dumazet
[not found] ` <1439993864.6610.11.camel-XN9IlZ5yJG9HTL0Zs8A6p/gx64E7kk8eUsxypvmhUTTZJqsBc5GL+g@public.gmane.org>
2015-08-19 14:22 ` Eric Dumazet
2015-08-19 17:05 ` Grumbach, Emmanuel
2015-08-19 12:59 ` [RFC v2 2/3] iwlwifi: mvm: allow to create A-MSDUs from a large send Emmanuel Grumbach
[not found] ` <1439989181-4444-1-git-send-email-emmanuel.grumbach-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2015-08-19 12:59 ` [RFC v2 3/3] iwlwifi: mvm: transfer the truesize to the last TSO segment Emmanuel Grumbach
[not found] ` <1439989181-4444-4-git-send-email-emmanuel.grumbach-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2015-08-19 14:24 ` Eric Dumazet
2015-08-19 19:17 ` Grumbach, Emmanuel
2015-08-19 20:39 ` Eric Dumazet
2015-08-20 6:21 ` Grumbach, Emmanuel
2015-08-20 13:11 ` Eric Dumazet
2015-08-20 13:53 ` Grumbach, Emmanuel
[not found] ` <0BA3FCBA62E2DC44AF3030971E174FB32E82654B-Jy8z56yoSI9wl47ZQwxUxrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2015-08-20 14:13 ` Eric Dumazet
2015-08-20 19:34 ` Grumbach, Emmanuel
[not found] ` <0BA3FCBA62E2DC44AF3030971E174FB32E8266E6-Jy8z56yoSI9wl47ZQwxUxrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2015-08-20 19:55 ` Eric Dumazet
2015-08-20 7:21 ` Grumbach, Emmanuel
2015-08-20 7:40 ` Grumbach, Emmanuel
2015-08-19 19:10 ` Sergei Shtylyov
2015-08-19 19:12 ` Grumbach, Emmanuel
[not found] ` <0BA3FCBA62E2DC44AF3030971E174FB32E8253B0-Jy8z56yoSI9wl47ZQwxUxrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2015-08-19 19:16 ` Sergei Shtylyov
2015-08-19 14:14 ` [RFC v2 0/3] add TSO / A-MSDU TX for iwlwifi Eric Dumazet
2015-08-19 15:07 ` Grumbach, Emmanuel
2015-08-19 16:08 ` Eric Dumazet
2015-08-19 17:00 ` Grumbach, Emmanuel
2015-08-19 17:19 ` Eric Dumazet
2015-08-19 17:56 ` Grumbach, Emmanuel [this message]
[not found] ` <0BA3FCBA62E2DC44AF3030971E174FB32E825252-Jy8z56yoSI9wl47ZQwxUxrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2015-08-19 18:01 ` Eric Dumazet
2015-08-19 18:09 ` Grumbach, Emmanuel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=0BA3FCBA62E2DC44AF3030971E174FB32E825252@hasmsx107.ger.corp.intel.com \
--to=emmanuel.grumbach-ral2jqcrhueavxtiumwx3w@public$(echo .)gmane.org \
--cc=eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public$(echo .)gmane.org \
--cc=ido-Ix1uc/W3ht7QT0dZR+AlfA@public$(echo .)gmane.org \
--cc=linux-wireless-u79uwXL29TY76Z2rM5mHXA@public$(echo .)gmane.org \
--cc=netdev-u79uwXL29TY76Z2rM5mHXA@public$(echo .)gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox