Messages in this thread | | | From | "G, GurucharanX" <> | Subject | RE: [Intel-wired-lan] [PATCH v2 2/2] igb: Make DMA faster when CPU is active on the PCIe link | Date | Tue, 14 Jun 2022 15:01:11 +0000 |
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> -----Original Message----- > From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of > Kai-Heng Feng > Sent: Wednesday, May 25, 2022 5:01 PM > To: Brandeburg, Jesse <jesse.brandeburg@intel.com>; Nguyen, Anthony L > <anthony.l.nguyen@intel.com> > Cc: linux-kernel@vger.kernel.org; Eric Dumazet <edumazet@google.com>; > Kai-Heng Feng <kai.heng.feng@canonical.com>; intel-wired- > lan@lists.osuosl.org; Jeff Kirsher <jeffrey.t.kirsher@intel.com>; > netdev@vger.kernel.org; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni > <pabeni@redhat.com>; David S. Miller <davem@davemloft.net> > Subject: [Intel-wired-lan] [PATCH v2 2/2] igb: Make DMA faster when CPU is > active on the PCIe link > > Intel I210 on some Intel Alder Lake platforms can only achieve ~750Mbps Tx > speed via iperf. The RR2DCDELAY shows around 0x2xxx DMA delay, which > will be significantly lower when 1) ASPM is disabled or 2) SoC package c-state > stays above PC3. When the RR2DCDELAY is around 0x1xxx the Tx speed can > reach to ~950Mbps. > > According to the I210 datasheet "8.26.1 PCIe Misc. Register - PCIEMISC", > "DMA Idle Indication" doesn't seem to tie to DMA coalesce anymore, so set it > to 1b for "DMA is considered idle when there is no Rx or Tx AND when there > are no TLPs indicating that CPU is active detected on the PCIe link (such as > the host executes CSR or Configuration register read or write operation)" and > performing Tx should also fall under "active CPU on PCIe link" case. > > In addition to that, commit b6e0c419f040 ("igb: Move DMA Coalescing init > code to separate function.") seems to wrongly changed from enabling > E1000_PCIEMISC_LX_DECISION to disabling it, also fix that. > > Fixes: b6e0c419f040 ("igb: Move DMA Coalescing init code to separate > function.") > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com> > --- > drivers/net/ethernet/intel/igb/igb_main.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) >
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
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