Re: [PATCH] atl1c: optimize rx loop

On Fri, Mar 19, 2021 at 05:15:35AM +0100, Willy Tarreau wrote:

On Fri, Mar 19, 2021 at 12:04:47PM +0800, Sieng Piaw Liew wrote:

quoted

Remove this trivial bit of inefficiency from the rx receive loop,
results in increase of a few Mbps in iperf3. Tested on Intel Core2
platform.

Signed-off-by: Sieng Piaw Liew <redacted>
---
 drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
index 3f65f2b370c5..b995f9a0479c 100644
--- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
+++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c

@@ -1796,9 +1796,7 @@ static void atl1c_clean_rx_irq(struct atl1c_adapter *adapter,
 	struct atl1c_recv_ret_status *rrs;
 	struct atl1c_buffer *buffer_info;
 
-	while (1) {
-		if (*work_done >= work_to_do)
-			break;
+	while (*work_done < work_to_do) {

It should not change anything, or only based on the compiler's optimization
and should not result in a measurable difference because what it does is
exactly the same. Have you really compared the compiled output code to
explain the difference ? I strongly suspect you'll find no difference at
all.

Thus for me it's certainly not an optimization, it could be qualified as
a cleanup to improve code readability however.

Willy

You're right. Objdump and diff showed no difference.

Regards,
Sieng Piaw