Re: [PATCH] net: stmmac: Improve Tx timer arm logic further
From: Maxime Chevallier <maxime.chevallier@bootlin.com>
Date: 2026-05-25 11:53:56
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linux-arm-kernel, lkml
Hi, On 5/25/26 08:16, muhammad.nazim.amirul.nazle.asmade@altera.com wrote:
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.
This description is a bit lacking on details wrt. the expensiveness and perf impacts, but I've tested with and without this patch on a cyclone V with dwmac-socfpga, and I cansee a diff when sending small UDP packets with : iperf3 -c <srv> -u -b 0 -l 64 Before this patch, around 45200 pps sent, after this patch, around 52300 pps sent ! Nice improvement :) So from my perspective, Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Maxime
quoted hunk ↗ jump to hunk
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); + } else { hrtimer_try_to_cancel(&tx_q->txtimer); + } } /**