diff options
| author | Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com> | 2026-05-29 09:46:59 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-06-03 05:20:48 +0300 |
| commit | edceeba4af3df39ec7e446e86ead50bbbbc85849 (patch) | |
| tree | abfd0fcd45af513de0863a165e3927c5a27e567d | |
| parent | 2d5c859f8e7173adc189ff2afe6ed1a7025ff322 (diff) | |
| download | linux-edceeba4af3df39ec7e446e86ead50bbbbc85849.tar.xz | |
net: stmmac: Improve Tx timer arm logic further
Calling hrtimer_start() on an already-active txtimer is unnecessary
and expensive. Skip the restart if the timer is already active by
adding an hrtimer_active() check before hrtimer_start().
Previously, each packet reset the timer to tx_coal_timer in the future,
acting as a sliding window that delayed NAPI under burst traffic. With
this change, an already-active timer is left to fire sooner, scheduling
NAPI within tx_coal_timer of the first packet and freeing TX descriptors
earlier.
There is no race concern: hrtimer_start() is internally serialized and
safe to call on an active timer. In the event of a race between
hrtimer_active() and hrtimer_start(), the worst case is calling
hrtimer_start() on an already-active timer, which is identical to the
pre-patch behaviour.
Performance on Cyclone V with dwmac-socfpga (iperf3 -u -b 0 -l 64):
Before: ~45200 pps
After: ~52300 pps (~15% improvement)
Additionally, ~10% improvement in UDP throughput observed on Agilex5,
with hrtimer CPU usage reduced from ~8% to ~0.6%.
Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260529064659.32287-1-muhammad.nazim.amirul.nazle.asmade@altera.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 12 |
1 files 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); + } } /** |