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Message-ID: <956879eb-a902-73dd-2574-1e6235571647@nbd.name>
Date: Sun, 26 Mar 2023 22:09:49 +0200
From: Felix Fietkau <nbd@....name>
To: Frank Wunderlich <frank-w@...lic-files.de>
Cc: netdev@...r.kernel.org, Daniel Golle <daniel@...rotopia.org>
Subject: Re: Aw: Re: Re: [PATCH net] net: ethernet: mtk_eth_soc: fix tx
throughput regression with direct 1G links
On 26.03.23 19:49, Frank Wunderlich wrote:
>> Gesendet: Sonntag, 26. März 2023 um 19:27 Uhr
>> Von: "Felix Fietkau" <nbd@....name>
>> An: "Frank Wunderlich" <frank-w@...lic-files.de>
>> Cc: netdev@...r.kernel.org, "Daniel Golle" <daniel@...rotopia.org>
>> Betreff: Re: Aw: Re: [PATCH net] net: ethernet: mtk_eth_soc: fix tx throughput regression with direct 1G links
>>
>> On 26.03.23 19:10, Frank Wunderlich wrote:
>> >> Gesendet: Sonntag, 26. März 2023 um 17:56 Uhr
>> >> Von: "Felix Fietkau" <nbd@....name>
>> >> An: "Frank Wunderlich" <frank-w@...lic-files.de>
>> >> Cc: netdev@...r.kernel.org, "Daniel Golle" <daniel@...rotopia.org>
>> >> Betreff: Re: Aw: [PATCH net] net: ethernet: mtk_eth_soc: fix tx throughput regression with direct 1G links
>> >>
>> >> On 25.03.23 10:28, Frank Wunderlich wrote:
>> >> >> Gesendet: Freitag, 24. März 2023 um 15:04 Uhr
>> >> >> Von: "Felix Fietkau" <nbd@....name>
>> >> >> An: netdev@...r.kernel.org
>> >> >> Cc: "Frank Wunderlich" <frank-w@...lic-files.de>, "Daniel Golle" <daniel@...rotopia.org>
>> >> >> Betreff: [PATCH net] net: ethernet: mtk_eth_soc: fix tx throughput regression with direct 1G links
>> >> >>
>> >> >> Using the QDMA tx scheduler to throttle tx to line speed works fine for
>> >> >> switch ports, but apparently caused a regression on non-switch ports.
>> >> >>
>> >> >> Based on a number of tests, it seems that this throttling can be safely
>> >> >> dropped without re-introducing the issues on switch ports that the
>> >> >> tx scheduling changes resolved.
>> >> >>
>> >> >> Link: https://lore.kernel.org/netdev/trinity-92c3826f-c2c8-40af-8339-bc6d0d3ffea4-1678213958520@3c-app-gmx-bs16/
>> >> >> Fixes: f63959c7eec3 ("net: ethernet: mtk_eth_soc: implement multi-queue support for per-port queues")
>> >> >> Reported-by: Frank Wunderlich <frank-w@...lic-files.de>
>> >> >> Reported-by: Daniel Golle <daniel@...rotopia.org>
>> >> >> Tested-by: Daniel Golle <daniel@...rotopia.org>
>> >> >> Signed-off-by: Felix Fietkau <nbd@....name>
>> >> >> ---
>> >> >> drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 --
>> >> >> 1 file changed, 2 deletions(-)
>> >> >>
>> >> >> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> >> >> index a94aa08515af..282f9435d5ff 100644
>> >> >> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> >> >> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> >> >> @@ -763,8 +763,6 @@ static void mtk_mac_link_up(struct phylink_config *config,
>> >> >> break;
>> >> >> }
>> >> >>
>> >> >> - mtk_set_queue_speed(mac->hw, mac->id, speed);
>> >> >> -
>> >> >> /* Configure duplex */
>> >> >> if (duplex == DUPLEX_FULL)
>> >> >> mcr |= MAC_MCR_FORCE_DPX;
>> >> >
>> >> > thx for the fix, as daniel already checked it on mt7986/bpi-r3 i tested bpi-r2/mt7623
>> >> >
>> >> > but unfortunately it does not fix issue on bpi-r2 where the gmac0/mt7530 part is affected.
>> >> >
>> >> > maybe it needs a special handling like you do for mt7621? maybe it is because the trgmii mode used on this path?
>> >> Could you please test if making it use the MT7621 codepath brings back
>> >> performance? I don't have any MT7623 hardware for testing right now.
>> >
>> > Hi,
>> >
>> > this seems to make the CPU stall (after kernel is loaded completely when userspace begins to start):
>> >
>> > - if (IS_ENABLED(CONFIG_SOC_MT7621)) {
>> > + if (IS_ENABLED(CONFIG_SOC_MT7621) || IS_ENABLED(CONFIG_SOC_MT7623)) {
>> >
>> > [ 27.252672] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
>> > [ 27.258618] rcu: 2-...0: (0 ticks this GP) idle=54c4/1/0x40000000 softir8
>> > [ 27.266973] rcu: (detected by 1, t=2102 jiffies, g=-891, q=7 ncpus=4)
>> > [ 27.273499] Sending NMI from CPU 1 to CPUs 2:
>> >
>> > [USBD] USB PRB0 LineState: 0
>> >
>> > wonder why this happens...i expected some kind of tranmit queue erros with trace...
>> >
>> > full log here
>> > https://pastebin.com/de4dZDt4
>> >
>> > but i've found no error there (sorry for cutting on the right side...my terminal window was to small)
>> The change you made has no effect, because CONFIG_SOC_MT7623 does not
>> exist, so there must be something else that broke your system.
>> Try CONFIG_MACH_MT7623 instead, once you've resolved the system hang.
>
> it was exactly this change above...dropping it fixed it
>
> do not know why i did no compile-error, looked into implementation of IS_ENABLED which is passed through different defines till
>
> include/linux/kconfig.h:42:#define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val)
> include/linux/kconfig.h:43:#define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0)
> include/linux/kconfig.h:14:#define __take_second_arg(__ignored, val, ...) val
>
> i do not expect that there is anything wrong, just wonder why this stalls...
>
> used the CONFIG_MACH_MT7623 (which is set in my config) boots up fine, but did not fix the 622Mbit-tx-issue
>
> and i'm not sure i have tested it before...all ports of mt7531 are affected, not only wan (i remembered you asked for this)
Does the MAC that's connected to the switch use flow control? Can you
test if changing that makes a difference?
- Felix
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