[PATCH net] gve: DQO: Remove incorrect prefetch

[PATCH net] gve: DQO: Remove incorrect prefetch

[Bailey Forrest]

The prefetch is incorrectly using the dma address instead of the virtual
address.

It's supposed to be:
prefetch((char *)buf_state->page_info.page_address +
	 buf_state->page_info.page_offset)

However, after correcting this mistake, there is no evidence of
performance improvement.

Fixes: 9b8dd5e5ea48 ("gve: DQO: Add RX path")
Signed-off-by: Bailey Forrest <bcf@google.com>
---
 drivers/net/ethernet/google/gve/gve_rx_dqo.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_rx_dqo.c b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
index 77bb8227f89b..8500621b2cd4 100644
--- a/drivers/net/ethernet/google/gve/gve_rx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
@@ -566,13 +566,6 @@ static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
 		return 0;
 	}
 
-	/* Prefetch the payload header. */
-	prefetch((char *)buf_state->addr + buf_state->page_info.page_offset);
-#if L1_CACHE_BYTES < 128
-	prefetch((char *)buf_state->addr + buf_state->page_info.page_offset +
-		 L1_CACHE_BYTES);
-#endif
-
 	if (eop && buf_len <= priv->rx_copybreak) {
 		rx->skb_head = gve_rx_copy(priv->dev, napi,
 					   &buf_state->page_info, buf_len, 0);
-- 
2.32.0.93.g670b81a890-goog

Re: [PATCH net] gve: DQO: Remove incorrect prefetch

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Thu,  1 Jul 2021 20:13:36 -0700 you wrote:
> The prefetch is incorrectly using the dma address instead of the virtual
> address.
> 
> It's supposed to be:
> prefetch((char *)buf_state->page_info.page_address +
> 	 buf_state->page_info.page_offset)
> 
> [...]

Here is the summary with links:
  - [net] gve: DQO: Remove incorrect prefetch
    https://git.kernel.org/netdev/net/c/1bfa4d0cb5ad

You are awesome, thank you!
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