Low 5 GHz performance of Intel Advanced-N 6230

Low 5 GHz performance of Intel Advanced-N 6230

[Julian Sikorski]

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Dear all,

I have been moderately recently hit by a performance drop of Intel
Advanced-N 6230 card. I unfortunately do not have the "before" numbers,
but I have noticed this since I was able to stream bluray rips over nfs
to a wired Raspberry Pi a while ago and now I cannot. This has lead me
to begin investigating the issue.
In the end I have used iperf3, testing speeds between RPi and laptop,
with laptop running both Windows and Linux. iperf3 on RPi was always the
same, on the laptop it was self-compiled iperf3 git master (on Windows I
used Cygwin). Please see the observed speeds below:
- Windows: upload to RPi 93 Mbit/s, download from RPi 54 Mbit/s
- Fedora: upload to RPi 26 Mbit/s, download from RPi 48 Mbit/s

This is all on Fedora 20 x86_64. Please find attached the journalctl log
for the last boot. Please let me know if more information is needed - I
would love to get my network speeds back up to the level where I can
watch bluray rips again. Thank you for your support in advance.

Best regards,
Julian

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Re: Low 5 GHz performance of Intel Advanced-N 6230

[Julian Sikorski]

W dniu 24.04.2014 08:10, Julian Sikorski pisze:
> Dear all,
> 
> I have been moderately recently hit by a performance drop of Intel
> Advanced-N 6230 card. I unfortunately do not have the "before" numbers,
> but I have noticed this since I was able to stream bluray rips over nfs
> to a wired Raspberry Pi a while ago and now I cannot. This has lead me
> to begin investigating the issue.
> In the end I have used iperf3, testing speeds between RPi and laptop,
> with laptop running both Windows and Linux. iperf3 on RPi was always the
> same, on the laptop it was self-compiled iperf3 git master (on Windows I
> used Cygwin). Please see the observed speeds below:
> - Windows: upload to RPi 93 Mbit/s, download from RPi 54 Mbit/s
> - Fedora: upload to RPi 26 Mbit/s, download from RPi 48 Mbit/s
> 
> This is all on Fedora 20 x86_64. Please find attached the journalctl log
> for the last boot. Please let me know if more information is needed - I
> would love to get my network speeds back up to the level where I can
> watch bluray rips again. Thank you for your support in advance.
> 
> Best regards,
> Julian
> 
Hello again,

I have narrowed this down to have regressed between 3.13.6-200.fc20 and
3.13.7-200. Using pointers from Josh Boyer of #fedora-devel, I have
managed to restore the previous performance by loading iwlwifi with
11n_disable=8. I am now at 3.14.1-200 with that option enabled and the
network is fast as it used to be.
Is such a major performance hit expected from this change? Here is the
commit in question:
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-3.13.y&id=45e5cb4f43d33e72ff5f98c80b081eb42e4e4182

Best regards,
Julian

Re: Low 5 GHz performance of Intel Advanced-N 6230

[Emmanuel Grumbach]

On 04/24/2014 07:24 PM, Julian Sikorski wrote:
> W dniu 24.04.2014 08:10, Julian Sikorski pisze:
>> Dear all,
>>
>> I have been moderately recently hit by a performance drop of Intel
>> Advanced-N 6230 card. I unfortunately do not have the "before" numbers,
>> but I have noticed this since I was able to stream bluray rips over nfs
>> to a wired Raspberry Pi a while ago and now I cannot. This has lead me
>> to begin investigating the issue.
>> In the end I have used iperf3, testing speeds between RPi and laptop,
>> with laptop running both Windows and Linux. iperf3 on RPi was always the
>> same, on the laptop it was self-compiled iperf3 git master (on Windows I
>> used Cygwin). Please see the observed speeds below:
>> - Windows: upload to RPi 93 Mbit/s, download from RPi 54 Mbit/s
>> - Fedora: upload to RPi 26 Mbit/s, download from RPi 48 Mbit/s
>>
>> This is all on Fedora 20 x86_64. Please find attached the journalctl log
>> for the last boot. Please let me know if more information is needed - I
>> would love to get my network speeds back up to the level where I can
>> watch bluray rips again. Thank you for your support in advance.
>>
>> Best regards,
>> Julian
>>
> Hello again,
> 
> I have narrowed this down to have regressed between 3.13.6-200.fc20 and
> 3.13.7-200. Using pointers from Josh Boyer of #fedora-devel, I have
> managed to restore the previous performance by loading iwlwifi with
> 11n_disable=8. I am now at 3.14.1-200 with that option enabled and the
> network is fast as it used to be.
> Is such a major performance hit expected from this change? Here is the
> commit in question:
> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-3.13.y&id=45e5cb4f43d33e72ff5f98c80b081eb42e4e4182
> 

Right - I disabled TX APMDU in this patch. This feature gives a big boost in TX performance, but lots of people experienced bugs that disappeared when this feature was disabled. This bug is in the firmware. Since the most common use case is to browse the internet which is more Rx than Tx, I decided to disabled this feature by default and allow people to enabled it using the module parameter.

Re: Low 5 GHz performance of Intel Advanced-N 6230

[Rafał Miłecki]

2014-04-25 9:46 GMT+02:00 Emmanuel Grumbach <egrumbach@gmail.com>:
> On 04/24/2014 07:24 PM, Julian Sikorski wrote:
>> Is such a major performance hit expected from this change? Here is the
>> commit in question:
>> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-3.13.y&id=45e5cb4f43d33e72ff5f98c80b081eb42e4e4182
>>
>
> Right - I disabled TX APMDU in this patch. This feature gives a big boost in TX performance, but lots of people experienced bugs that disappeared when this feature was disabled. This bug is in the firmware. Since the most common use case is to browse the internet which is more Rx than Tx, I decided to disabled this feature by default and allow people to enabled it using the module parameter.

Any plans to update (fix) the firmware?

-- 
Rafał

Re: Low 5 GHz performance of Intel Advanced-N 6230

[Emmanuel Grumbach]

On 04/25/2014 12:15 PM, Rafał Miłecki wrote:
> 2014-04-25 9:46 GMT+02:00 Emmanuel Grumbach <egrumbach@gmail.com>:
>> On 04/24/2014 07:24 PM, Julian Sikorski wrote:
>>> Is such a major performance hit expected from this change? Here is the
>>> commit in question:
>>> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-3.13.y&id=45e5cb4f43d33e72ff5f98c80b081eb42e4e4182
>>>
>>
>> Right - I disabled TX APMDU in this patch. This feature gives a big boost in TX performance, but lots of people experienced bugs that disappeared when this feature was disabled. This bug is in the firmware. Since the most common use case is to browse the internet which is more Rx than Tx, I decided to disabled this feature by default and allow people to enabled it using the module parameter.
> 
> Any plans to update (fix) the firmware?
> 

I don't work on the firmware level, so I can't really say, but I doubt someone will have the cycles to fix the firmware for these devices. Newer devices (7260 and up) have this feature enabled.

Re: Low 5 GHz performance of Intel Advanced-N 6230

[Julian Sikorski]

W dniu 25.04.2014 11:51, Emmanuel Grumbach pisze:
> 
> 
> On 04/25/2014 12:15 PM, Rafał Miłecki wrote:
>> 2014-04-25 9:46 GMT+02:00 Emmanuel Grumbach <egrumbach@gmail.com>:
>>> On 04/24/2014 07:24 PM, Julian Sikorski wrote:
>>>> Is such a major performance hit expected from this change? Here is the
>>>> commit in question:
>>>> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-3.13.y&id=45e5cb4f43d33e72ff5f98c80b081eb42e4e4182
>>>>
>>>
>>> Right - I disabled TX APMDU in this patch. This feature gives a big boost in TX performance, but lots of people experienced bugs that disappeared when this feature was disabled. This bug is in the firmware. Since the most common use case is to browse the internet which is more Rx than Tx, I decided to disabled this feature by default and allow people to enabled it using the module parameter.
>>
>> Any plans to update (fix) the firmware?
>>
> 
> I don't work on the firmware level, so I can't really say, but I doubt someone will have the cycles to fix the firmware for these devices. Newer devices (7260 and up) have this feature enabled.
> 
Can this feature be disabled on a per-device basis? It clearly works for
6230 and is a huge performance hit when gone.

Julian

Re: Low 5 GHz performance of Intel Advanced-N 6230

[Emmanuel Grumbach]

On 04/26/2014 01:27 AM, Julian Sikorski wrote:
> W dniu 25.04.2014 11:51, Emmanuel Grumbach pisze:
>>
>>
>> On 04/25/2014 12:15 PM, Rafał Miłecki wrote:
>>> 2014-04-25 9:46 GMT+02:00 Emmanuel Grumbach <egrumbach@gmail.com>:
>>>> On 04/24/2014 07:24 PM, Julian Sikorski wrote:
>>>>> Is such a major performance hit expected from this change? Here is the
>>>>> commit in question:
>>>>> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-3.13.y&id=45e5cb4f43d33e72ff5f98c80b081eb42e4e4182
>>>>>
>>>>
>>>> Right - I disabled TX APMDU in this patch. This feature gives a big boost in TX performance, but lots of people experienced bugs that disappeared when this feature was disabled. This bug is in the firmware. Since the most common use case is to browse the internet which is more Rx than Tx, I decided to disabled this feature by default and allow people to enabled it using the module parameter.
>>>
>>> Any plans to update (fix) the firmware?
>>>
>>
>> I don't work on the firmware level, so I can't really say, but I doubt someone will have the cycles to fix the firmware for these devices. Newer devices (7260 and up) have this feature enabled.
>>
> Can this feature be disabled on a per-device basis? It clearly works for
> 6230 and is a huge performance hit when gone.
> 

It works for you - but for others it didn't.