Re: [PATCH net-next 4/4] net: stmmac: Always use TX coalesce timer value when rescheduling

On Mon, 16 Dec 2019 09:20:53 +0000, Jose Abreu wrote:

quoted

quoted

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f61780ae30ac..726a17d9cc35 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1975,7 +1975,7 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
 
 	/* We still have pending packets, let's call for a new scheduling */
 	if (tx_q->dirty_tx != tx_q->cur_tx)
-		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(10));
+		mod_timer(&tx_q->txtimer, STMMAC_COAL_TIMER(priv->tx_coal_timer));  

I think intent of this code is to re-check the ring soon. The same
value of 10 is used in stmmac_tx_timer() for quick re-check.

tx_coal_timer defaults to 1000, so it's quite a jump from 10 to 1000.

I think the commit message leaves too much unsaid.

Also if you want to change to the ethtool timeout value, could you move 
stmmac_tx_timer_arm() and reuse that helper?  

Yeah, it's a quick re-check but 10us can be too low on some speeds and 
leads to CPU useless-looping. The intent is to let this always be 
configurable by user.

Okay, please do mention the bump from 10us to the default of 1ms in the
commit message, though.