[net-next PATCH v3 0/4] net: stmmac: improve tx timer logic

Christian Marangi
2023-10-14T09:30:33Z

This series comes with the intention of restoring original performance
of stmmac on some router/device that used the stmmac driver to handle
gigabit traffic.

More info are present in patch 3. This cover letter is to show results
and improvements of the following change.

The move to hr_timer for tx timer and commit 8fce33317023 ("net: stmmac:
Rework coalesce timer and fix multi-queue races") caused big performance
regression on these kind of device.

This was observed on ipq806x that after kernel 4.19 couldn't handle
gigabit speed anymore.

The following series is currently applied and tested in OpenWrt SNAPSHOT
and have great performance increase. (the scenario is qca8k switch +
stmmac dwmac1000) Some good comparison can be found here [1].

The difference is from a swconfig scenario (where dsa tagging is not
used so very low CPU impact in handling traffic) and DSA scenario where
tagging is used and there is a minimal impact in the CPU. As can be
notice even with DSA in place we have better perf.

It was observed by other user that also SQM scenario with cake scheduler
were improved in the order of 100mbps (this scenario is CPU limited and
any increase of perf is caused by removing load on the CPU)

Been at least 15 days that this is in use without any complain or bug
reported about queue timeout. (was the case with v1 before the
additional patch was added, only appear on real world tests and not on
iperf tests)

[1] https://forum.openwrt.org/t/netgear-r7800-exploration-ipq8065-qca9984/285/3427?u=ansuel

Changes v3:
- Fix compilation error for missing comma
Changes v2:
- Add patch to move tx timer arm outside tx clean.

Christian Marangi (4):
net: introduce napi_is_scheduled helper
net: stmmac: improve TX timer arm logic
net: stmmac: move TX timer arm after DMA enable
net: stmmac: increase TX coalesce timer to 5ms

drivers/net/ethernet/chelsio/cxgb3/sge.c | 8 ----
drivers/net/ethernet/stmicro/stmmac/common.h | 2 +-
.../net/ethernet/stmicro/stmmac/stmmac_main.c | 37 +++++++++++++++----
drivers/net/wireless/realtek/rtw89/core.c | 2 +-
include/linux/netdevice.h | 23 ++++++++++++
net/core/dev.c | 2 +-
6 files changed, 56 insertions(+), 18 deletions(-)

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2.40.1