From: Ben Greear <greearb@candelatech.com>
To: Eric Dumazet <edumazet@google.com>
Cc: netdev <netdev@vger.kernel.org>
Subject: Re: net: tso: add UDP segmentation support: adds regression for ax200 upload
Date: Thu, 17 Dec 2020 09:56:33 -0800 [thread overview]
Message-ID: <adbee2ec-c6ba-7a17-eb98-1c53365fa911@candelatech.com> (raw)
In-Reply-To: <CANn89iKpa1y2SKJuR9kRi=AZs94sj+-tzRs+2D0vmxh+ahEcGA@mail.gmail.com>
On 12/17/20 2:11 AM, Eric Dumazet wrote:
> On Thu, Dec 17, 2020 at 12:59 AM Ben Greear <greearb@candelatech.com> wrote:
>>
>> On 12/16/20 3:09 PM, Ben Greear wrote:
>>> Hello Eric,
>>>
>>> The patch below evidently causes TCP throughput to be about 50Mbps instead of 700Mbps
>>> when using ax200 to upload tcp traffic.
>>>
>>> When I disable TSO, performance goes back up to around 700Mbps.
>>
>> As a followup, when I revert the patch, upload speed goes to ~900Mbps,
>> so even better than just disabling TSO (I left TSO enabled after reverting the patch).
>>
>> Thanks,
>> Ben
>>
>
> Thanks for the report !
>
> It seems drivers/net/wireless/intel/iwlwifi/pcie/tx.c:iwl_fill_data_tbs_amsdu()
> calls tso_build_hdr() with extra bytes (SNAP header),
> it is not yet clear to me what is broken :/
Your patch is guessing tcp vs udp by looking at header length
from what I could tell. So if something uses a different size,
it probably gets confused?
>
> Can you confirm which driver is used for ax200 ?
>
> I see tso_build_hdr() also being used from
> drivers/net/wireless/intel/iwlwifi/queue/tx.c
I tested against the un-modified ax200 5.10.0 kernel driver, and it has the issue.
The ax200 backports release/core56 driver acts a bit different (poorer performance over all than
in-kernel driver), but has similar upstream issues that are mitigated by
disabling TSO.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2020-12-17 17:57 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 23:09 net: tso: add UDP segmentation support: adds regression for ax200 upload Ben Greear
2020-12-16 23:59 ` Ben Greear
2020-12-17 10:11 ` Eric Dumazet
2020-12-17 17:56 ` Ben Greear [this message]
2020-12-17 18:07 ` Eric Dumazet
2020-12-17 18:13 ` Ben Greear
2020-12-17 18:20 ` Eric Dumazet
2020-12-17 20:40 ` Ben Greear
2020-12-18 20:16 ` Jakub Kicinski
2020-12-19 15:18 ` Johannes Berg
2020-12-19 16:55 ` Ben Greear
2020-12-21 18:46 ` Eric Dumazet
2020-12-21 18:54 ` Jakub Kicinski
2020-12-21 19:04 ` Eric Dumazet
2020-12-21 19:14 ` Eric Dumazet
2020-12-21 20:01 ` Rainer Suhm
2020-12-24 17:48 ` Ben Greear
2021-01-19 8:53 ` Johannes Berg
2021-01-19 10:02 ` Eric Dumazet
2021-01-25 14:57 ` Johannes Berg
2021-01-25 14:58 ` Eric Dumazet
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