On Wednesday 27 March 2019 at 15:05:46 +0000, Mike Crowe wrote: > After upgrading the kernel to v4.19 we started seeing increased packet > latency on two machines with ASUS H87M-E motherboards with on-board Realtek > Gigabit Ethernet. This didn't happen with v4.18. (More details, including > kernel log and lspci output at > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925496 ) > > Bisecting revealed that commit > > a99790bf5c7f3d68d8b01e015d3212a98ee7bd57 r8169: Reinstate ASPM Support > > provoked this change in behaviour. > > If I patch v4.9.31's drivers/net/ethernet/realtek/r8169.c > rtl_hw_aspm_clkreq_enable function to never enable the clocks (which, > AFAICT, is equivalent to reverting the aforementioned commit) then packet > latency is normal. > > The increased packet latency can also be resolved by: > > 1. Running 'ethtool -C eth0 rx-usecs 0 rx-frames 1' > > 2. Disabling "EPU Power Saving Mode" in the BIOS (on the Ai Tweaker page.) > This option is enabled when the "ASUS Optimal" setting is selected on > the BIOS front page. > > but neither of these solutions are ideal because they require the user to > realise that there's a problem and discover these solutions. > > Is there a way to fix the code to work correctly with this motherboard even > with "EPU Power Saving Mode" enabled?
Unfortunately, my searching prior to sending that email did not reveal that this problem has been reported before[1]. Apologies for the noise. Mike. [1] https://lore.kernel.org/netdev/camlo_r7q6qcr7kx5goovj_bzdlu_tnw3ukmkzwdml4c2bhu...@mail.gmail.com/
