[Cake] pie in dd-wrt

Toke Høiland-Jørgensen toke at redhat.com
Thu Aug 22 06:12:47 EDT 2019

Sebastian Gottschall <s.gottschall at newmedia-net.de> writes:

> Am 21.08.2019 um 23:39 schrieb Toke Høiland-Jørgensen:
>> Sebastian Gottschall <s.gottschall at newmedia-net.de> writes:
>>> Am 21.08.2019 um 18:21 schrieb Sebastian Moeller:
>>>> On August 21, 2019 6:12:03 PM GMT+02:00, Sebastian Gottschall <s.gottschall at newmedia-net.de> wrote:
>>>>> thats rather old. i rewrote all the qos code in the last 4 or 5 days.
>>>>> so
>>>>> things might be changed. next phase is bringing all the link level
>>>>> detail configuration stuff into the gui which will be done
>>>>> tomorrow or at least still within this week.
>>>>> i also added now cake to some smaller low budged routers with limited
>>>>> resources, so see how it runs. i had bad experiences with fq_codel in
>>>>> the past due some high memory usage.
>>>>> especially since its hard coded somewhat into the wireless ath9k
>>>>> driver.
>>>>> so i already modded it for more efficient handling. 4 mb max per queue
>>>>> is simply too much for  a 32 mb ram based router.
>>>> This is why I'm sqm we reduced the queued packet maximum m to around 1000, and also why cake has an explicit memlimit keyword.
>>> yeah but does this help if fq_codel is hardcoded into mac80211? fq_codel
>>> has a memlimit  keyword too btw. its fixed to 4MB. i reduced it to 256kb
>>> on low memory architectures. no other way to get around OOM problems
>>> mac80211  does always make use of fq_codel. it has a own build in
>>> implementation
>> The mac80211 implementation also has a memlimit parameter. You can set
>> it through debugfs - 2MB would be:
>> echo 2097152 > /sys/kernel/debug/ieee80211/phy0/aqm
>> or through iw:
>> iw phy phy0 set txq memory_limit 2097152
>> The nl80211 attribute is called NL80211_ATTR_TXQ_MEMORY_LIMIT.
> as i said i already modified mac80211 in a way that it sets sane memory 
> limits depending on the architecture. devices with just 32 mb ram run 
> only stable with 256kb memory limit.
> so i configured different defaults. but the point is still that for a 
> standard user (lets say in openwrt) the current implementation is not 
> good. somewhere in the openwrt community i was reading that such devices 
> should not be used anymore for openwrt due the memory limitations. but 
> thats no solution for me if it was working before the introduction of 
> fq_codel in mac80211

... which is why it is configurable?


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