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Subject[PATCH net-next 2/2] net: ethernet: ti: am65-cpsw: use napi_complete_done() in TX completion
Date
This patch enables support for hard irqs deferral feature from Eric Dumazet
[1] for TI K3 CPSW driver by using napi_complete_done() in TX completion
path.

Depending on gro_flush_timeout and napi_defer_hard_irqs at gives up to 30%
CPU utilization reduction:

gro_flush_timeout=50000
napi_defer_hard_irqs=2

netperf -l 10 -H 192.168.1.1 -t UDP_STREAM -c -C -- -m 1470
MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.1.1 () port 0 AF_INET
Socket Message Elapsed Messages CPU Service
Size Size Time Okay Errors Throughput Util Demand
bytes bytes secs # # 10^6bits/sec % SS us/KB

before:
212992 1470 10.00 809632 0 952.0 42.98 14.792
212992 10.00 809630 952.0 50.66 8.719

after:
212992 1470 10.00 813686 0 956.8 32.14 11.009
212992 10.00 813686 956.8 50.05 8.570

[1] https://lore.kernel.org/netdev/20200422161329.56026-1-edumazet@google.com/

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
drivers/net/ethernet/ti/am65-cpsw-nuss.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index 08399f572091..b18343f9791d 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -1086,13 +1086,13 @@ static int am65_cpsw_nuss_tx_poll(struct napi_struct *napi_tx, int budget)
else
num_tx = am65_cpsw_nuss_tx_compl_packets(tx_chn->common, tx_chn->id, budget);

- num_tx = min(num_tx, budget);
- if (num_tx < budget) {
- napi_complete(napi_tx);
+ if (num_tx >= budget)
+ return budget;
+
+ if (napi_complete_done(napi_tx, num_tx))
enable_irq(tx_chn->irq);
- }

- return num_tx;
+ return 0;
}

static irqreturn_t am65_cpsw_nuss_rx_irq(int irq, void *dev_id)
--
2.17.1
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