[#9] Kernel panic with SQM scripts - Comment added

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FS#9 - Kernel panic with SQM scripts
User who did this - moeller0 (moeller0)

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Dear All,

Please let me try to answer a few of the questions above:

Why is cake not the default?
Cake is not per-se "better" than htb+fq_codel and cake is still under (more or less) active development so it certainly is not yet ready for becoming the default. Simple.qos with its combination of HTB and fq_codel still is the recommended default, so unless you want to participate in active debugging and development please stick to simple.qos or simplest.qos.

Why cake is not included?
Cake just became available as an easy to install kernel module in LEDE to allow wider testing. But since it is not (yet) recommended as default it also is not installed by default (people might be unhappy if sqm-scripts would install unnecessary modules wasting their space).

Does cake use less CPU than HTB+fq_codel?
Some time last year tests with an earlier version of cake indicated that in a CPU limited situation cake might allow a higher overall shaper bandwidth than the default HTB+fq_codel combination. More recent tests are not that conclusive. Especially it was shown that HTB behaves differently from HFSC and cake in CPU limited mode: HTB will keep the added latency low, sacrificing more bandwidth (sometimes considerably more bandwidth) while the other two shaper sacrifice less bandwidth but will also increase the latency under load (or show more bufferbloat).

What about sqm-scripts-extra scripts?
The sqm-scripts extra scripts are really just for wider testing, please do not relay on them being available for longer times/.

[OT] SQM-scripts-exts: What is the difference between the _LAN_ and _WAN_ variants?
Cake promises much better isolation of internal host IPs versus each other than the other qdiscs. But to be able to implement per-internal-host-IP fairness cake needs to see the internal IPs, in the typical home situation sqm gets instantiated on the WAN interface that typically also performs NAT for IPv4. Cake will only be able to see one internal address if instantiated there, making per-internal-IP isolation degrade into the default per-flw isolation. To allow to test whether cake's two relevant isolation options (triple and dual) actually work in the real world the _LAN_ scripts are prepared to be instantiated on internal LAN interfaces of a home router, since on the LAN ports the internal IPs are still visible. Please note that typically the bridged WLAN interfaces will not be covered by the shaping, making the LAN variant scripts not generally recommended solutions, but pure testing devices. The ideal test would be to hook upp another switch/dumbAP behind the shaped LAN port and try to mix traffic from different host and see if for example heavy bit-torrenting still badly affects the connections of other internal hosts. If anybody actually tests this, please report any results as issues under https://github.com/tohojo/sqm-scripts thanks in advance
[/OT]
Best Regards
        M.

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https://bugs.lede-project.org/index.php?do=details&task_id=9#comment53