[LibreQoS] In BPF pping - so far

dan dandenson at gmail.com
Wed Oct 19 11:49:32 EDT 2022 

Those 'efficiency' threads in Intel 12th gen should probably be addressed
as well.  You can't turn them off in BIOS.

On Wed, Oct 19, 2022 at 8:48 AM Robert Chacón via LibreQoS <
libreqos at lists.bufferbloat.net> wrote:

> Awesome work on this!
> I suspect there should be a slight performance bump once Hyperthreading is
> disabled and efficient power management is off.
> Hyperthreading/SMT always messes with HTB performance when I leave it on.
> Thank you for mentioning that - I now went ahead and added instructions on
> disabling hyperthreading on the Wiki for new users.
> Super promising results!
> Interested to see what throughput is with xdp-cpumap-tc vs cpumap-pping.
> So far in your VM setup it seems to be doing very well.
>
> On Wed, Oct 19, 2022 at 8:06 AM Herbert Wolverson via LibreQoS <
> libreqos at lists.bufferbloat.net> wrote:
>
>> Also, I forgot to mention that I *think* the current version has removed
>> the requirement that the inbound
>> and outbound classifiers be placed on the same CPU. I know interduo was
>> particularly keen on packing
>> upload into fewer cores. I'll add that to my list of things to test.
>>
>> On Wed, Oct 19, 2022 at 9:01 AM Herbert Wolverson <herberticus at gmail.com>
>> wrote:
>>
>>> I'll definitely take a look - that does look interesting. I don't have
>>> X11 on any of my test VMs, but
>>> it looks like it can work without the GUI.
>>>
>>> Thanks!
>>>
>>> On Wed, Oct 19, 2022 at 8:58 AM Dave Taht <dave.taht at gmail.com> wrote:
>>>
>>>> could I coax you to adopt flent?
>>>>
>>>> apt-get install flent netperf irtt fping
>>>>
>>>> You sometimes have to compile netperf yourself with --enable-demo on
>>>> some systems.
>>>> There are a bunch of python libs neede for the gui, but only on the
>>>> client.
>>>>
>>>> Then you can run a really gnarly test series and plot the results over
>>>> time.
>>>>
>>>> flent --socket-stats --step-size=.05 -t 'the-test-conditions' -H
>>>> the_server_name rrul # 110 other tests
>>>>
>>>>
>>>> On Wed, Oct 19, 2022 at 6:44 AM Herbert Wolverson via LibreQoS
>>>> <libreqos at lists.bufferbloat.net> wrote:
>>>> >
>>>> > Hey,
>>>> >
>>>> > Testing the current version (
>>>> https://github.com/thebracket/cpumap-pping-hackjob ), it's doing
>>>> better than I hoped. This build has shared (not per-cpu) maps, and a
>>>> userspace daemon (xdp_pping) to extract and reset stats.
>>>> >
>>>> > My testing environment has grown a bit:
>>>> > * ShaperVM - running Ubuntu Server and LibreQoS, with the new
>>>> cpumap-pping-hackjob version of xdp-cpumap.
>>>> > * ExtTest - running Ubuntu Server, set as 10.64.1.1. Hosts an iperf
>>>> server.
>>>> > * ClientInt1 - running Ubuntu Server (minimal), set as 10.64.1.2.
>>>> Hosts iperf client.
>>>> > * ClientInt2 - running Ubuntu Server (minimal), set as 10.64.1.3.
>>>> Hosts iperf client.
>>>> >
>>>> > ClientInt1, ClientInt2 and one interface (LAN facing) of ShaperVM are
>>>> on a virtual switch.
>>>> > ExtTest and the other interface (WAN facing) of ShaperVM are on a
>>>> different virtual switch.
>>>> >
>>>> > These are all on a host machine running Windows 11, a core i7 12th
>>>> gen, 32 Gb RAM and fast SSD setup.
>>>> >
>>>> > TEST 1: DUAL STREAMS, LOW THROUGHPUT
>>>> >
>>>> > For this test, LibreQoS is configured:
>>>> > * Two APs, each with 5gbit/s max.
>>>> > * 100.64.1.2 and 100.64.1.3 setup as CPEs, each limited to about
>>>> 100mbit/s. They map to 1:5 and 2:5 respectively (separate CPUs).
>>>> > * Set to use Cake
>>>> >
>>>> > On each client, roughly simultaneously run: iperf -c 100.64.1.1 -t
>>>> 500 (for a long run). Running xdp_pping yields correct results:
>>>> >
>>>> > [
>>>> > {"tc":"1:5", "avg" : 4, "min" : 3, "max" : 5, "samples" : 11},
>>>> > {"tc":"2:5", "avg" : 4, "min" : 3, "max" : 5, "samples" : 11},
>>>> > {}]
>>>> >
>>>> > Or when I waited a while to gather/reset:
>>>> >
>>>> > [
>>>> > {"tc":"1:5", "avg" : 4, "min" : 3, "max" : 6, "samples" : 60},
>>>> > {"tc":"2:5", "avg" : 4, "min" : 3, "max" : 5, "samples" : 60},
>>>> > {}]
>>>> >
>>>> > The ShaperVM shows no errors, just periodic logging that it is
>>>> recording data.  CPU is about 2-3% on two CPUs, zero on the others (as
>>>> expected).
>>>> >
>>>> > After 500 seconds of continual iperfing, each client reported a
>>>> throughput of 104 Mbit/sec and 6.06 GBytes of data transmitted.
>>>> >
>>>> > So for smaller streams, I'd call this a success.
>>>> >
>>>> > TEST 2: DUAL STREAMS, HIGH THROUGHPUT
>>>> >
>>>> > For this test, LibreQoS is configured:
>>>> > * Two APs, each with 5gb/s max.
>>>> > * 100.64.1.2 and 100.64.1.3 setup as CPEs, each limited to 5Gbit/s!
>>>> Mapped to 1:5 and 2:5 respectively (separate CPUs).
>>>> >
>>>> > Run iperfc -c 100.64.1.1 -t 500 on each client at the same time.
>>>> >
>>>> > xdp_pping shows results, too:
>>>> >
>>>> > [
>>>> > {"tc":"1:5", "avg" : 4, "min" : 1, "max" : 7, "samples" : 58},
>>>> > {"tc":"2:5", "avg" : 7, "min" : 3, "max" : 11, "samples" : 58},
>>>> > {}]
>>>> >
>>>> > [
>>>> > {"tc":"1:5", "avg" : 5, "min" : 4, "max" : 8, "samples" : 13},
>>>> > {"tc":"2:5", "avg" : 8, "min" : 7, "max" : 10, "samples" : 13},
>>>> > {}]
>>>> >
>>>> > The ShaperVM shows two CPUs pegging between 70 and 90 percent.
>>>> >
>>>> > After 500 seconds of continual iperfing, each client reported a
>>>> throughput of 2.72 Gbits/sec (158 GBytes) and 3.89 Gbits/sec and 226 GBytes.
>>>> >
>>>> > Maxing out HyperV like this is inducing a bit of latency (which is to
>>>> be expected), but it's not bad. I also forgot to disable hyperthreading,
>>>> and looking at the host performance it is sometimes running the second
>>>> virtual CPU on an underpowered "fake" CPU.
>>>> >
>>>> > So for two large streams, I think we're doing pretty well also!
>>>> >
>>>> > TEST 3: DUAL STREAMS, SINGLE CPU
>>>> >
>>>> > This test is designed to try and blow things up. It's the same as
>>>> test 2, but both CPEs are set to the same CPU (1), using TC handles 1:5 and
>>>> 1:6.
>>>> >
>>>> > ShaperVM CPU1 maxed out in the high 90s, the other CPUs were idle.
>>>> The pping stats start to show a bit of degradation in performance for
>>>> pounding it so hard:
>>>> >
>>>> > [
>>>> > {"tc":"1:6", "avg" : 10, "min" : 9, "max" : 19, "samples" : 24},
>>>> > {"tc":"1:5", "avg" : 10, "min" : 8, "max" : 18, "samples" : 24},
>>>> > {}]
>>>> >
>>>> > For whatever reason, it smoothed out over time:
>>>> >
>>>> > [
>>>> > {"tc":"1:6", "avg" : 10, "min" : 9, "max" : 12, "samples" : 50},
>>>> > {"tc":"1:5", "avg" : 10, "min" : 8, "max" : 13, "samples" : 50},
>>>> > {}]
>>>> >
>>>> > Surprisingly (to me), I didn't encounter errors. Each client received
>>>> 2.22 Gbit/s performance, over 129 Gbytes of data.
>>>> >
>>>> > TEST 4: DUAL STREAMS, 50 SUB-STREAMS
>>>> >
>>>> > This test is also designed to break things. Same as test 3, but using
>>>> iperf -c 100.64.1.1 -P 50 -t 120 - 50 substreams, to try and really tax the
>>>> flow tracking. (Shorter time window because I really wanted to go and find
>>>> coffee)
>>>> >
>>>> > ShaperVM CPU sat at around 80-97%, tending towards 97%. pping results
>>>> show that this torture test is worsening performance, and there's always
>>>> lots of samples in the buffer:
>>>> >
>>>> > [
>>>> > {"tc":"1:6", "avg" : 23, "min" : 19, "max" : 27, "samples" : 49},
>>>> > {"tc":"1:5", "avg" : 24, "min" : 19, "max" : 27, "samples" : 49},
>>>> > {}]
>>>> >
>>>> > This test also ran better than I expected. You can definitely see
>>>> some latency creeping in as I make the system work hard. Each VM showed
>>>> around 2.4 Gbit/s in total performance at the end of the iperf session.
>>>> There's definitely some latency creeping in, which is expected - but I'm
>>>> not sure I expected quite that much.
>>>> >
>>>> > WHAT'S NEXT & CONCLUSION
>>>> >
>>>> > I noticed that I forgot to turn off efficient power management on my
>>>> VMs and host, and left Hyperthreading on by mistake. So that hurts overall
>>>> performance.
>>>> >
>>>> > The base system seems to be working pretty solidly, at least for
>>>> small tests.Next up, I'll be removing extraneous debug reporting code,
>>>> removing some code paths that don't do anything but report, and looking for
>>>> any small optimization opportunities. I'll then re-run these tests. Once
>>>> that's done, I hope to find a maintenance window on my WISP and try it with
>>>> actual traffic.
>>>> >
>>>> > I also need to re-run these tests without the pping system to provide
>>>> some before/after analysis.
>>>> >
>>>> > On Tue, Oct 18, 2022 at 1:01 PM Herbert Wolverson <
>>>> herberticus at gmail.com> wrote:
>>>> >>
>>>> >> It's probably not entirely thread-safe right now (ran into some
>>>> issues reading per_cpu maps back from userspace; hopefully, I'll get that
>>>> figured out) - but the commits I just pushed have it basically working on
>>>> single-stream testing. :-)
>>>> >>
>>>> >> Setup cpumap as usual, and periodically run xdp-pping. This gives
>>>> you per-connection RTT information in JSON:
>>>> >>
>>>> >> [
>>>> >> {"tc":"1:5", "avg" : 5, "min" : 5, "max" : 5, "samples" : 1},
>>>> >> {}]
>>>> >>
>>>> >> (With the extra {} because I'm not tracking the tail and haven't
>>>> done comma removal). The tool also empties the various maps used to gather
>>>> data, acting as a "reset" point. There's a max of 60 samples per queue, in
>>>> a ringbuffer setup (so newest will start to overwrite the oldest).
>>>> >>
>>>> >> I'll start trying to test on a larger scale now.
>>>> >>
>>>> >> On Mon, Oct 17, 2022 at 3:34 PM Robert Chacón <
>>>> robert.chacon at jackrabbitwireless.com> wrote:
>>>> >>>
>>>> >>> Hey Herbert,
>>>> >>>
>>>> >>> Fantastic work! Super exciting to see this coming together,
>>>> especially so quickly.
>>>> >>> I'll test it soon.
>>>> >>> I understand and agree with your decision to omit certain features
>>>> (ICMP tracking,DNS tracking, etc) to optimize performance for our use case.
>>>> Like you said, in order to merge the functionality without a performance
>>>> hit, merging them is sort of the only way right now. Otherwise there would
>>>> be a lot of redundancy and lost throughput for an ISP's use. Though
>>>> hopefully long term there will be a way to keep all projects working
>>>> independently but interoperably with a plugin system of some kind.
>>>> >>>
>>>> >>> By the way, I'm making some headway on LibreQoS v1.3. Focusing on
>>>> optimizations for high sub counts (8000+ subs) as well as stateful changes
>>>> to the queue structure.
>>>> >>> I'm working to set up a physical lab to test high throughput and
>>>> high client count scenarios.
>>>> >>> When testing beyond ~32,000 filters we get "no space left on
>>>> device" from xdp-cpumap-tc, which I think relates to the bpf map size
>>>> limitation you mentioned. Maybe in the coming months we can take a look at
>>>> that.
>>>> >>>
>>>> >>> Anyway great work on the cpumap-pping program! Excited to see more
>>>> on this.
>>>> >>>
>>>> >>> Thanks,
>>>> >>> Robert
>>>> >>>
>>>> >>> On Mon, Oct 17, 2022 at 12:45 PM Herbert Wolverson via LibreQoS <
>>>> libreqos at lists.bufferbloat.net> wrote:
>>>> >>>>
>>>> >>>> Hey,
>>>> >>>>
>>>> >>>> My current (unfinished) progress on this is now available here:
>>>> https://github.com/thebracket/cpumap-pping-hackjob
>>>> >>>>
>>>> >>>> I mean it about the warnings, this isn't at all stable, debugged -
>>>> and can't promise that it won't unleash the nasal demons
>>>> >>>> (to use a popular C++ phrase). The name is descriptive! ;-)
>>>> >>>>
>>>> >>>> With that said, I'm pretty happy so far:
>>>> >>>>
>>>> >>>> * It runs only on the classifier - which xdp-cpumap-tc has nicely
>>>> shunted onto a dedicated CPU. It has to run on both
>>>> >>>>   the inbound and outbound classifiers, since otherwise it would
>>>> only see half the conversation.
>>>> >>>> * It does assume that your ingress and egress CPUs are mapped to
>>>> the same interface; I do that anyway in BracketQoS. Not doing
>>>> >>>>   that opens up a potential world of pain, since writes to the
>>>> shared maps would require a locking scheme. Too much locking, and you lose
>>>> all of the benefit of using multiple CPUs to begin with.
>>>> >>>> * It is pretty wasteful of RAM, but most of the shaper systems
>>>> I've worked with have lots of it.
>>>> >>>> * I've been gradually removing features that I don't want for
>>>> BracketQoS. A hypothetical future "useful to everyone" version wouldn't do
>>>> that.
>>>> >>>> * Rate limiting is working, but I removed the requirement for a
>>>> shared configuration provided from userland - so right now it's always set
>>>> to report at 1 second intervals per stream.
>>>> >>>>
>>>> >>>> My testbed is currently 3 Hyper-V VMs - a simple "client" and
>>>> "world", and a "shaper" VM in between running a slightly hacked-up LibreQoS.
>>>> >>>> iperf from "client" to "world" (with Libre set to allow 10gbit/s
>>>> max, via a cake/HTB queue setup) is around 5 gbit/s at present, on my
>>>> >>>> test PC (the host is a core i7, 12th gen, 12 cores - 64gb RAM and
>>>> fast SSDs)
>>>> >>>>
>>>> >>>> Output currently consists of debug messages reading:
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   515.399222:
>>>> bpf_trace_printk: (tc) Flow open event
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   515.399239:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 374696
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   515.399466:
>>>> bpf_trace_printk: (tc) Flow open event
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   515.399475:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 247069
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   516.405151:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 5217155
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   517.405248:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 4515394
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   518.406117:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 4481289
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   519.406255:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 4255268
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   520.407864:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 5249493
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   521.406664:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 3795993
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   522.407469:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 3949519
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   523.408126:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 4365335
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   524.408929:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 4154910
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   525.410048:
>>>> bpf_trace_printk: (tc) Send performance event (5,1), 4405582
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   525.434080:
>>>> bpf_trace_printk: (tc) Send flow event
>>>> >>>>   cpumap/0/map:4-1371    [000] D..2.   525.482714:
>>>> bpf_trace_printk: (tc) Send flow event
>>>> >>>>
>>>> >>>> The times haven't been tweaked yet. The (5,1) is tc handle
>>>> major/minor, allocated by the xdp-cpumap parent.
>>>> >>>> I get pretty low latency between VMs; I'll set up a test with some
>>>> real-world data very soon.
>>>> >>>>
>>>> >>>> I plan to keep hacking away, but feel free to take a peek.
>>>> >>>>
>>>> >>>> Thanks,
>>>> >>>> Herbert
>>>> >>>>
>>>> >>>> On Mon, Oct 17, 2022 at 10:14 AM Simon Sundberg <
>>>> Simon.Sundberg at kau.se> wrote:
>>>> >>>>>
>>>> >>>>> Hi, thanks for adding me to the conversation. Just a couple of
>>>> quick
>>>> >>>>> notes.
>>>> >>>>>
>>>> >>>>> On Mon, 2022-10-17 at 16:13 +0200, Toke Høiland-Jørgensen wrote:
>>>> >>>>> > [ Adding Simon to Cc ]
>>>> >>>>> >
>>>> >>>>> > Herbert Wolverson via LibreQoS <libreqos at lists.bufferbloat.net>
>>>> writes:
>>>> >>>>> >
>>>> >>>>> > > Hey,
>>>> >>>>> > >
>>>> >>>>> > > I've had some pretty good success with merging xdp-pping (
>>>> >>>>> > >
>>>> https://github.com/xdp-project/bpf-examples/blob/master/pping/pping.h )
>>>> >>>>> > > into xdp-cpumap-tc (
>>>> https://github.com/xdp-project/xdp-cpumap-tc ).
>>>> >>>>> > >
>>>> >>>>> > > I ported over most of the xdp-pping code, and then changed
>>>> the entry point
>>>> >>>>> > > and packet parsing code to make use of the work already done
>>>> in
>>>> >>>>> > > xdp-cpumap-tc (it's already parsed a big chunk of the packet,
>>>> no need to do
>>>> >>>>> > > it twice). Then I switched the maps to per-cpu maps, and had
>>>> to pin them -
>>>> >>>>> > > otherwise the two tc instances don't properly share data.
>>>> >>>>> > >
>>>> >>>>>
>>>> >>>>> I guess the xdp-cpumap-tc ensures that the same flow is processed
>>>> on
>>>> >>>>> the same CPU core at both ingress or egress. Otherwise, if a flow
>>>> may
>>>> >>>>> be processed by different cores on ingress and egress the per-CPU
>>>> maps
>>>> >>>>> will not really work reliably as each core will have a different
>>>> view
>>>> >>>>> on the state of the flow, if there's been a previous packet with a
>>>> >>>>> certain TSval from that flow etc.
>>>> >>>>>
>>>> >>>>> Furthermore, if a flow is always processed on the same core (on
>>>> both
>>>> >>>>> ingress and egress) I think per-CPU maps may be a bit wasteful on
>>>> >>>>> memory. From my understanding the keys for per-CPU maps are still
>>>> >>>>> shared across all CPUs, it's just that each CPU gets its own
>>>> value. So
>>>> >>>>> all CPUs will then have their own data for each flow, but it's
>>>> only the
>>>> >>>>> CPU processing the flow that will have any relevant data for the
>>>> flow
>>>> >>>>> while the remaining CPUs will just have an empty state for that
>>>> flow.
>>>> >>>>> Under the same assumption that packets within the same flow are
>>>> always
>>>> >>>>> processed on the same core there should generally not be any
>>>> >>>>> concurrency issues with having a global (non-per-CPU) either as
>>>> packets
>>>> >>>>> from the same flow cannot be processed concurrently then (and
>>>> thus no
>>>> >>>>> concurrent access to the same value in the map). I am however
>>>> still
>>>> >>>>> very unclear on if there's any considerable performance impact
>>>> between
>>>> >>>>> global and per-CPU map versions if the same key is not accessed
>>>> >>>>> concurrently.
>>>> >>>>>
>>>> >>>>> > > Right now, output
>>>> >>>>> > > is just stubbed - I've still got to port the perfmap output
>>>> code. Instead,
>>>> >>>>> > > I'm dumping a bunch of extra data to the kernel debug pipe,
>>>> so I can see
>>>> >>>>> > > roughly what the output would look like.
>>>> >>>>> > >
>>>> >>>>> > > With debug enabled and just logging I'm now getting about 4.9
>>>> Gbits/sec on
>>>> >>>>> > > single-stream iperf between two VMs (with a shaper VM in the
>>>> middle). :-)
>>>> >>>>> >
>>>> >>>>> > Just FYI, that "just logging" is probably the biggest source of
>>>> >>>>> > overhead, then. What Simon found was that sending the data from
>>>> kernel
>>>> >>>>> > to userspace is one of the most expensive bits of epping, at
>>>> least when
>>>> >>>>> > the number of data points goes up (which is does as additional
>>>> flows are
>>>> >>>>> > added).
>>>> >>>>>
>>>> >>>>> Yhea, reporting individual RTTs when there's lots of them (you
>>>> may get
>>>> >>>>> upwards of 1000 RTTs/s per flow) is not only problematic in terms
>>>> of
>>>> >>>>> direct overhead from the tool itself, but also becomes demanding
>>>> for
>>>> >>>>> whatever you use all those RTT samples for (i.e. need to log,
>>>> parse,
>>>> >>>>> analyze etc. a very large amount of RTTs). One way to deal with
>>>> that is
>>>> >>>>> of course to just apply some sort of sampling (the
>>>> -r/--rate-limit and
>>>> >>>>> -R/--rtt-rate
>>>> >>>>> >
>>>> >>>>> > > So my question: how would you prefer to receive this data?
>>>> I'll have to
>>>> >>>>> > > write a daemon that provides userspace control (periodic
>>>> cleanup as well as
>>>> >>>>> > > reading the performance stream), so the world's kinda our
>>>> oyster. I can
>>>> >>>>> > > stick to Kathie's original format (and dump it to a named
>>>> pipe, perhaps?),
>>>> >>>>> > > a condensed format that only shows what you want to use, an
>>>> efficient
>>>> >>>>> > > binary format if you feel like parsing that...
>>>> >>>>> >
>>>> >>>>> > It would be great if we could combine efforts a bit here so we
>>>> don't
>>>> >>>>> > fork the codebase more than we have to. I.e., if "upstream"
>>>> epping and
>>>> >>>>> > whatever daemon you end up writing can agree on data format etc
>>>> that
>>>> >>>>> > would be fantastic! Added Simon to Cc to facilitate this :)
>>>> >>>>> >
>>>> >>>>> > Briefly what I've discussed before with Simon was to have the
>>>> ability to
>>>> >>>>> > aggregate the metrics in the kernel (WiP PR [0]) and have a
>>>> userspace
>>>> >>>>> > utility periodically pull them out. What we discussed was doing
>>>> this
>>>> >>>>> > using an LPM map (which is not in that PR yet). The idea would
>>>> be that
>>>> >>>>> > userspace would populate the LPM map with the keys (prefixes)
>>>> they
>>>> >>>>> > wanted statistics for (in LibreQOS context that could be one
>>>> key per
>>>> >>>>> > customer, for instance). Epping would then do a map lookup into
>>>> the LPM,
>>>> >>>>> > and if it gets a match it would update the statistics in that
>>>> map entry
>>>> >>>>> > (keeping a histogram of latency values seen, basically).
>>>> Simon's PR
>>>> >>>>> > below uses this technique where userspace will "reset" the
>>>> histogram
>>>> >>>>> > every time it loads it by swapping out two different map
>>>> entries when it
>>>> >>>>> > does a read; this allows you to control the sampling rate from
>>>> >>>>> > userspace, and you'll just get the data since the last time you
>>>> polled.
>>>> >>>>>
>>>> >>>>> Thank's Toke for summarzing both the current state and the plan
>>>> going
>>>> >>>>> forward. I will just note that this PR (and all my other work with
>>>> >>>>> ePPing/BPF-PPing/XDP-PPing/I-suck-at-names-PPing) will be more or
>>>> less
>>>> >>>>> on hold for a couple of weeks right now as I'm trying to finish
>>>> up a
>>>> >>>>> paper.
>>>> >>>>>
>>>> >>>>> > I was thinking that if we all can agree on the map format, then
>>>> your
>>>> >>>>> > polling daemon could be one userspace "client" for that, and
>>>> the epping
>>>> >>>>> > binary itself could be another; but we could keep compatibility
>>>> between
>>>> >>>>> > the two, so we don't duplicate effort.
>>>> >>>>> >
>>>> >>>>> > Similarly, refactoring of the epping code itself so it can be
>>>> plugged
>>>> >>>>> > into the cpumap-tc code would be a good goal...
>>>> >>>>>
>>>> >>>>> Should probably do that...at some point. In general I think it's
>>>> a bit
>>>> >>>>> of an interesting problem to think about how to chain multiple
>>>> XDP/tc
>>>> >>>>> programs together in an efficent way. Most XDP and tc programs
>>>> will do
>>>> >>>>> some amount of packet parsing and when you have many chained
>>>> programs
>>>> >>>>> parsing the same packets this obviously becomes a bit wasteful.
>>>> In the
>>>> >>>>> same time it would be nice if one didn't need to manually merge
>>>> >>>>> multiple programs together into a single one like this to get rid
>>>> of
>>>> >>>>> this duplicated parsing, or at least make that process of merging
>>>> those
>>>> >>>>> programs as simple as possible.
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> > -Toke
>>>> >>>>> >
>>>> >>>>> > [0] https://github.com/xdp-project/bpf-examples/pull/59
>>>> >>>>>
>>>> >>>>> När du skickar e-post till Karlstads universitet behandlar vi
>>>> dina personuppgifter<https://www.kau.se/gdpr>.
>>>> >>>>> When you send an e-mail to Karlstad University, we will process
>>>> your personal data<https://www.kau.se/en/gdpr>.
>>>> >>>>
>>>> >>>> _______________________________________________
>>>> >>>> LibreQoS mailing list
>>>> >>>> LibreQoS at lists.bufferbloat.net
>>>> >>>> https://lists.bufferbloat.net/listinfo/libreqos
>>>> >>>
>>>> >>>
>>>> >>>
>>>> >>> --
>>>> >>> Robert Chacón
>>>> >>> CEO | JackRabbit Wireless LLC
>>>> >
>>>> > _______________________________________________
>>>> > LibreQoS mailing list
>>>> > LibreQoS at lists.bufferbloat.net
>>>> > https://lists.bufferbloat.net/listinfo/libreqos
>>>>
>>>>
>>>>
>>>> --
>>>> This song goes out to all the folk that thought Stadia would work:
>>>>
>>>> https://www.linkedin.com/posts/dtaht_the-mushroom-song-activity-6981366665607352320-FXtz
>>>> Dave Täht CEO, TekLibre, LLC
>>>>
>>> _______________________________________________
>> LibreQoS mailing list
>> LibreQoS at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/libreqos
>>
>
>
> --
> Robert Chacón
> CEO | JackRabbit Wireless LLC <http://jackrabbitwireless.com>
> _______________________________________________
> LibreQoS mailing list
> LibreQoS at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/libreqos
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.bufferbloat.net/pipermail/libreqos/attachments/20221019/dddd5085/attachment-0001.html>

More information about the LibreQoS mailing list