no ~931 is the restriction... ( not cpu )
ive never used pie... should be cake for that shaper...
off-topic-note: realized recently that script should really be called;
ctinfo_8layercake_rpi4.qos
due to it instantiating with diffserv8... but i'm happy to just keep the name aligned with where it was pilfered from for provinence reasoning...
i've never really provided much guidance for the SQM-CONFIG setting for use with that script...
verbage
partly because i'm not sure what it can support... but for reference... i've always used it with a bone standard up/down on single wan with practically no other options...
sqm.wan=queue
sqm.wan.interface='eth1'
sqm.wan.download='49470'
sqm.wan.upload='16980'
sqm.wan.linklayer='none'
sqm.wan.enabled='1'
sqm.wan.qdisc='cake'
sqm.wan.script='ctinfo_4layercake_rpi4.qos'
sqm.wan.debug_logging='1'
sqm.wan.verbosity='5'
up to you... but you need to ressign eth0 interrupt affinity (or use packet_steering ) to achieve max throughput...
verbage
i (got off my rear) ran controlled 'internal-fake-GB-wan' testing yesterday ( @dlakelan did so a long time ago ) with and without sqm... so we know where the main impediments are... we just don't know what is 'perfect'-value-s/sane-default/alternate nic behavior... which is something only a user comfortable with messing with IRQ etc. can really assist with... even with my mediocre ( witness-me ) skills its difficult to isolate or interpret tweaking all of these values...
fwiw... i'm now semi-randomly setting...
echo -n c > /proc/irq/32/smp_affinity
echo -n c > /proc/irq/33/smp_affinity
echo -n a > /sys/class/net/eth0/queues/*/*_cpus
and to avoid panic / confusion... most of this is only really relevant for people with WAN OVER ~250-350Mb/s hence why it took me so long to dig into this at all...