[Intel-wired-lan] I226-V 1G limited to ~250Mbit with ASPM enabled

ValdikSS iam at valdikss.org.ru
Mon Dec 9 09:21:00 UTC 2024


>> After (presumably) latest UEFI v0033 update for the NUC, my network is 
>> limited to ~250 Mbit/s download unless I disable PCIE ASPM option in 
>> UEFI settings.
>> 56:00.0 Ethernet controller [0200]: Intel Corporation Ethernet 
>> Controller I226-V [8086:125c] (rev 04)
> 
> Hello,
> 
> I believe that the issue you are facing is related to PCIE L1.2 state 
> exit latency. To confirm this please try to reproduce it after making 
> the following changes in the igc code:
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_i225.c 
> b/drivers/net/ethernet/intel/igc/igc_i225.c
> index 0dd61719f1ed..1c0c3d665a0c 100644
> --- a/drivers/net/ethernet/intel/igc/igc_i225.c
> +++ b/drivers/net/ethernet/intel/igc/igc_i225.c
> @@ -612,6 +612,10 @@ s32 igc_set_ltr_i225(struct igc_hw *hw, bool link)
>                   */
>                  ltr_min = (1000 * size) / speed;
>                  ltr_max = ltr_min + tw_system;
> +               if (speed == SPEED_1000) {
> +                       ltr_min = ltr_max = 100 * 1000;
> +               }
> +
>                  scale_min = (ltr_min / 1024) < 1024 ? 
> IGC_LTRMINV_SCALE_1024 :
>                              IGC_LTRMINV_SCALE_32768;
>                  scale_max = (ltr_max / 1024) < 1024 ? 
> IGC_LTRMAXV_SCALE_1024 :

That instantly fixed the issue, thanks!

With the patch:

$ curl -o /dev/null http://speedtest.selectel.ru/1GB -4
   % Total    % Received % Xferd  Average Speed   Time    Time     Time 
Current
                                  Dload  Upload   Total   Spent    Left 
Speed
100 1024M  100 1024M    0     0  55.3M      0  0:00:18  0:00:18 --:--:-- 
59.5M

Without the patch:

$ curl -o /dev/null http://speedtest.selectel.ru/1GB -4
   % Total    % Received % Xferd  Average Speed   Time    Time     Time 
Current
                                  Dload  Upload   Total   Spent    Left 
Speed
100 1024M  100 1024M    0     0  21.8M      0  0:00:46  0:00:46 --:--:-- 
20.1M
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