On 2024-09-03 14:14:58 +0200, Alexander Lobakin wrote:

From: Mohamed Khalfella <redacted>
Date: Fri, 30 Aug 2024 11:01:19 -0700

quoted

On 2024-08-30 15:07:45 +0200, Alexander Lobakin wrote:

quoted

From: Mohamed Khalfella <redacted>
Date: Thu, 29 Aug 2024 15:38:56 -0600

quoted

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/pci_vsc.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/pci_vsc.c
index 6b774e0c2766..bc6c38a68702 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/pci_vsc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/pci_vsc.c

@@ -269,6 +269,7 @@ int mlx5_vsc_gw_read_block_fast(struct mlx5_core_dev *dev, u32 *data,
 {
 	unsigned int next_read_addr = 0;
 	unsigned int read_addr = 0;
+	unsigned int count = 0;
 
 	while (read_addr < length) {
 		if (mlx5_vsc_gw_read_fast(dev, read_addr, &next_read_addr,

@@ -276,6 +277,9 @@ int mlx5_vsc_gw_read_block_fast(struct mlx5_core_dev *dev, u32 *data,
 			return read_addr;
 
 		read_addr = next_read_addr;
+		/* Yield the cpu every 128 register read */
+		if ((++count & 0x7f) == 0)
+			cond_resched();

Why & 0x7f, could it be written more clearly?

		if (++count == 128) {
			cond_resched();
			count = 0;
		}

Also, I'd make this open-coded value a #define somewhere at the
beginning of the file with a comment with a short explanation.

This is still valid.

Done. See <1>.

quoted

What you are suggesting should work also. I copied the style from
mlx5_vsc_wait_on_flag() to keep the code consistent. The comment above
the line should make it clear.

I just don't see a reason to make the code less readable.

<1> Now I am looking at mlx5_vsc_wait_on_flag() again, I realized the 
code does not want to reset retries to 0 because it needs to check when
it reaches VSC_MAX_RETRIES. This is not the case here. I will update the
code as suggested.

quoted

quoted

BTW, why 128? Not 64, not 256 etc? You just picked it, I don't see any
explanation in the commitmsg or here in the code why exactly 128. Have
you tried different values?

This mostly subjective. For the numbers I saw in the lab, this will
release the cpu after ~4.51ms. If crdump takes ~5s, the code should
release the cpu after ~18.0ms. These numbers look reasonable to me.

So just mention in the commit message that you tried different values
and 128 gave you the best results.

I will update the commit message in v3.