[PATCHv2] net: dpaa:reduce number of synchronize_net() calls

[PATCHv2] net: dpaa:reduce number of synchronize_net() calls

[Xi Huang]

In the function dpaa_napi_del(), we execute the netif_napi_del()
for each cpu, which is actually a high overhead operation
because each call to netif_napi_del() contains a synchronize_net(),
i.e. an RCU operation. In fact, it is only necessary to call
 __netif_napi_del and use synchronize_net() once outside of the loop.
This change is similar to commit 2543a6000e593a ("gro_cells: reduce
number of synchronize_net() calls") and commit 5198d545dba8ad (" net:
remove napi_hash_del() from driver-facing API") 5198d545db.

Signed-off-by: Xi Huang <xuiagnh@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
V1 -> V2: Modify the cited commit format and remove useless information

 drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
index cfe6b57b1..5d99cfb4e 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
@@ -3156,8 +3156,9 @@ static void dpaa_napi_del(struct net_device *net_dev)
 	for_each_possible_cpu(cpu) {
 		percpu_priv = per_cpu_ptr(priv->percpu_priv, cpu);
 
-		netif_napi_del(&percpu_priv->np.napi);
+		__netif_napi_del(&percpu_priv->np.napi);
 	}
+	synchronize_net();
 }
 
 static inline void dpaa_bp_free_pf(const struct dpaa_bp *bp,
-- 
2.34.1

Re: [PATCHv2] net: dpaa:reduce number of synchronize_net() calls

[Jakub Kicinski]

On Thu, 22 Aug 2024 15:20:42 +0800 Xi Huang wrote:
> In the function dpaa_napi_del(), we execute the netif_napi_del()
> for each cpu, which is actually a high overhead operation
> because each call to netif_napi_del() contains a synchronize_net(),
> i.e. an RCU operation. In fact, it is only necessary to call
>  __netif_napi_del and use synchronize_net() once outside of the loop.
> This change is similar to commit 2543a6000e593a ("gro_cells: reduce
> number of synchronize_net() calls") and commit 5198d545dba8ad (" net:
> remove napi_hash_del() from driver-facing API") 5198d545db.
> 
> Signed-off-by: Xi Huang <xuiagnh@gmail.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>

You missed the part of Eric's response that told you to wait 24 hours:
https://www.kernel.org/doc/html/next/process/maintainer-netdev.html
-- 
pv-bot: 24h

Re: [PATCHv2] net: dpaa:reduce number of synchronize_net() calls

[XI HUANG]

I am very sorry, I misunderstood the meaning of “Please send a V2 in
~24 hours”, I mistakenly thought that it could be sent within 24
hours. Do I need to resend the patchv2 24 hours after the first
patchv1?Sorry again and thanks so much for the heads up!

Re: [PATCHv2] net: dpaa:reduce number of synchronize_net() calls

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 22 Aug 2024 15:20:42 +0800 you wrote:
> In the function dpaa_napi_del(), we execute the netif_napi_del()
> for each cpu, which is actually a high overhead operation
> because each call to netif_napi_del() contains a synchronize_net(),
> i.e. an RCU operation. In fact, it is only necessary to call
>  __netif_napi_del and use synchronize_net() once outside of the loop.
> This change is similar to commit 2543a6000e593a ("gro_cells: reduce
> number of synchronize_net() calls") and commit 5198d545dba8ad (" net:
> remove napi_hash_del() from driver-facing API") 5198d545db.
> 
> [...]

Here is the summary with links:
  - [PATCHv2] net: dpaa:reduce number of synchronize_net() calls
    https://git.kernel.org/netdev/net-next/c/2c163922de69

You are awesome, thank you!
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