net: stmmac: Use hrtimer for TX coalescing

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This driver uses a normal timer for TX coalescing, which means that the
with the default tx-usecs of 1000 microseconds the cleanups actually
happen 10 ms or more later with HZ=100.  This leads to very low
througput with TCP when bridged to a slow link such as a 4G modem.  Fix
this by using an hrtimer instead.

On my ARM platform with HZ=100 and the default TX coalescing settings
(tx-frames 25 tx-usecs 1000), with "tc qdisc add dev eth0 root netem
delay 60ms 40ms rate 50Mbit" run on the server, netperf's TCP_STREAM
improves from ~5.5 Mbps to ~100 Mbps.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20201120150208.6838-1-vincent.whitchurch@axis.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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This commit is contained in:

Vincent Whitchurch 2020-11-20 16:02:08 +01:00 • committed by Jakub Kicinski

parent 5112cf59d7

commit d5a05e69ac

2 changed files with 16 additions and 10 deletions

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3

drivers/net/ethernet/stmicro/stmmac/stmmac.h

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23

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

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