Re: [PATCH] net: stmmac: Improve Tx timer arm logic further
From: Andrew Lunn <andrew@lunn.ch>
Date: 2026-05-25 13:47:06
Also in:
linux-arm-kernel, lkml
On Sun, May 24, 2026 at 11:16:53PM -0700, muhammad.nazim.amirul.nazle.asmade@altera.com wrote:
quoted hunk ↗ jump to hunk
From: Nazim Amirul <redacted> Currently hrtimer_start is called even if hrtimer is active. This is unnecessary and expensive in some targets. This patch avoids calling hrtimer_start unnecessarily. Signed-off-by: Rohan G Thomas <redacted> Signed-off-by: Nazim Amirul <redacted> --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 3591755ea30b..35da51c26248 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c@@ -3341,12 +3341,14 @@ static void stmmac_tx_timer_arm(struct stmmac_priv *priv, u32 queue) * Try to cancel any timer if napi is scheduled, timer will be armed * again in the next scheduled napi. */ - if (unlikely(!napi_is_scheduled(napi))) - hrtimer_start(&tx_q->txtimer, - STMMAC_COAL_TIMER(tx_coal_timer), - HRTIMER_MODE_REL); - else + if (unlikely(!napi_is_scheduled(napi))) { + if (unlikely(!(hrtimer_active(&tx_q->txtimer)))) + hrtimer_start(&tx_q->txtimer, + STMMAC_COAL_TIMER(tx_coal_timer), + HRTIMER_MODE_REL);
Is there a race condition here? I've not thought about it enough to
know if there is/is not.
Also, does this change the meaning of tx_coal_timer?
I think the commit message needs expanding, to cover these issues. For
performance changes, it is also normal to include some performance
numbers, before/after, in the commit message.
Andrew
---
pw-bot: cr