[PATCH v2] i40e: drop useless bitmap_weight() call in i40e_set_rxfh_fields()
From: Yury Norov (NVIDIA)
Date: Wed Dec 17 2025 - 20:58:09 EST
bitmap_weight() is O(N) and useless here, because the following
for_each_set_bit() returns immediately in case of empty flow_pctypes.
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@xxxxxxxxx>
---
v1: https://lore.kernel.org/all/20251216002852.334561-1-yury.norov@xxxxxxxxx/
v2: don't drop flow_id (Aleksandr).
.../net/ethernet/intel/i40e/i40e_ethtool.c | 21 +++++++------------
1 file changed, 8 insertions(+), 13 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
index f2c2646ea298..e64880b6b047 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
@@ -3637,6 +3637,7 @@ static int i40e_set_rxfh_fields(struct net_device *netdev,
((u64)i40e_read_rx_ctl(hw, I40E_PFQF_HENA(1)) << 32);
DECLARE_BITMAP(flow_pctypes, FLOW_PCTYPES_SIZE);
u64 i_set, i_setc;
+ u8 flow_id;
bitmap_zero(flow_pctypes, FLOW_PCTYPES_SIZE);
@@ -3720,20 +3721,14 @@ static int i40e_set_rxfh_fields(struct net_device *netdev,
return -EINVAL;
}
- if (bitmap_weight(flow_pctypes, FLOW_PCTYPES_SIZE)) {
- u8 flow_id;
+ for_each_set_bit(flow_id, flow_pctypes, FLOW_PCTYPES_SIZE) {
+ i_setc = (u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id)) |
+ ((u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id)) << 32);
+ i_set = i40e_get_rss_hash_bits(&pf->hw, nfc, i_setc);
- for_each_set_bit(flow_id, flow_pctypes, FLOW_PCTYPES_SIZE) {
- i_setc = (u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id)) |
- ((u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id)) << 32);
- i_set = i40e_get_rss_hash_bits(&pf->hw, nfc, i_setc);
-
- i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id),
- (u32)i_set);
- i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id),
- (u32)(i_set >> 32));
- hena |= BIT_ULL(flow_id);
- }
+ i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id), (u32)i_set);
+ i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id), (u32)(i_set >> 32));
+ hena |= BIT_ULL(flow_id);
}
i40e_write_rx_ctl(hw, I40E_PFQF_HENA(0), (u32)hena);
--
2.43.0