Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
net: enetc: take the MDIO lock only once per NAPI poll cycle
commit 6d36ecd upstream. The workaround for the ENETC MDIO erratum caused a performance degradation of 82 Kpps (seen with IP forwarding of two 1Gbps streams of 64B packets). This is due to excessive locking and unlocking in the fast path, which can be avoided. By taking the MDIO read-side lock only once per NAPI poll cycle, we are able to regain 54 Kpps (65%) of the performance hit. The rest of the performance degradation comes from the TX data path, but unfortunately it doesn't look like we can optimize that away easily, even with netdev_xmit_more(), there just isn't any skb batching done, to help with taking the MDIO lock less often than once per packet. We need to change the register accessor type for enetc_get_tx_tstamp, because it now runs under the enetc_lock_mdio as per the new call path detailed below: enetc_msix -> napi_schedule -> enetc_poll -> enetc_lock_mdio -> enetc_clean_tx_ring -> enetc_get_tx_tstamp -> enetc_clean_rx_ring -> enetc_unlock_mdio Fixes: fd5736b ("enetc: Workaround for MDIO register access issue") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
- Loading branch information
1 parent
5fb230e
commit ff96626
Showing
2 changed files
with
11 additions
and
22 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters