On 2021/5/27 8:00, Jakub Kicinski wrote:

On Wed, 26 May 2021 17:27:40 +0800 Huazhong Tan wrote:

quoted

Currently, there many drivers who support CQE mode configuration,
some configure it as a fixed when initialized, some provide an
interface to change it by ethtool private flags. In order make it
more generic, add 'ETHTOOL_A_COALESCE_USE_CQE_TX' and
'ETHTOOL_A_COALESCE_USE_CQE_RX' attribute and expand struct
kernel_ethtool_coalesce with use_cqe_mode_tx and use_cqe_mode_rx,
then these parameters can be accessed by ethtool netlink coalesce
uAPI.

Signed-off-by: Huazhong Tan <redacted>

diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index 25131df..975394e 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst

@@ -937,6 +937,8 @@ Kernel response contents:
    ``ETHTOOL_A_COALESCE_TX_USECS_HIGH``         u32     delay (us), high Tx
    ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_HIGH``    u32     max packets, high Tx
    ``ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL``  u32     rate sampling interval
+  ``ETHTOOL_A_COALESCE_USE_CQE_TX``	       bool    Tx CQE mode
+  ``ETHTOOL_A_COALESCE_USE_CQE_RX``	       bool    Rx CQE mode
    ===========================================  ======  =======================
  
  Attributes are only included in reply if their value is not zero or the

@@ -975,6 +977,8 @@ Request contents:
    ``ETHTOOL_A_COALESCE_TX_USECS_HIGH``         u32     delay (us), high Tx
    ``ETHTOOL_A_COALESCE_TX_MAX_FRAMES_HIGH``    u32     max packets, high Tx
    ``ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL``  u32     rate sampling interval
+  ``ETHTOOL_A_COALESCE_USE_CQE_TX``	       bool    Tx CQE mode
+  ``ETHTOOL_A_COALESCE_USE_CQE_RX``	       bool    Rx CQE mode
    ===========================================  ======  =======================
  
  Request is rejected if it attributes declared as unsupported by driver (i.e.

You need to thoroughly document the semantics. Can you point us to
which drivers/devices implement similar modes of operation (if they
exist we need to make sure semantics match)?

Ok, will complement the semantics.


Currently, only mlx5 provides a interface to update
this mode through ethtool priv-flag. other drivers like
broadcom and ice just use a fixed EQE and do not have
update interface.

quoted

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 1030540..9d0a386 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h

@@ -179,6 +179,8 @@ __ethtool_get_link_ksettings(struct net_device *dev,
  
  struct kernel_ethtool_coalesce {
  	struct ethtool_coalesce	base;
+	__u32	use_cqe_mode_tx;
+	__u32	use_cqe_mode_rx;

No __ in front, this is not a user space structure.
Why not bool or a bitfield?

bool is enough, __u32 is used here to be consistent with

fields in struct ethtool_coalesce.

This seems unnecessary?

quoted

  };
  
  /**

@@ -216,6 +223,8 @@ const struct nla_policy ethnl_coalesce_set_policy[] = {
  	[ETHTOOL_A_COALESCE_TX_USECS_HIGH]	= { .type = NLA_U32 },
  	[ETHTOOL_A_COALESCE_TX_MAX_FRAMES_HIGH]	= { .type = NLA_U32 },
  	[ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL] = { .type = NLA_U32 },
+	[ETHTOOL_A_COALESCE_USE_CQE_MODE_TX]	= { .type = NLA_U8 },
+	[ETHTOOL_A_COALESCE_USE_CQE_MODE_RX]	= { .type = NLA_U8 },

This needs a policy to make sure values are <= 1.

.