WiFi mysteries resolved once and for all — Power saving is clearly the culprit!


porg

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I hope that this report helps to resolve almost all mysteries related to WiFi issues on the Pandora once and for all!

 

To cut it short: Power saving is the culprit!

Without energy management on the internal WiFi one gets reliable 500-800 KB/sec!

The causal connection is explicit! Have had experience with 3 Pandoras (2 Originals, 1 Rebirth),

now, thanks to Pandora System Info (sysinfo), I eventually got substantiating monitoring data!

Cannot tell about the 1Ghz device though.

 

 

 

WiFi EXPERIENCE ON MY 3 PANDORAS

 

I had 3 Pandoras — 2 Originals, and now a Rebirth — and out of the box, WiFi merely worked for all of them! But the good news: It can reliably be solved software-wise, right now only at the cost of disabling WiFi power saving and having a shorter battery runtime, but probably some clever coder can improve the WiFi power saving algorithm, which I think, a shrink would describe as "a patient, with highly suicidal tendencies". (Explanation further below)

 

My first Original Pandora (OP1CC, 2011-05) had bad WiFi out of the box, but after discovering how to disable power saving, it worked fine with speeds about 900 KB/sec. Just my memories, no data noted. Back then, I did not systematically troubleshoot this. Lack of a network link did not catch my attention too much, because there was no PNDManager yet, and also web browsing did not work too well (without memory swap, which I did not know as an improver for web browsing). OP1CC suffered the purple tint of death, and I sent it in for repair.

 

My second Original Pandora (OP2CC, 2012-09) was quite bad from the beginning, discharging very quickly, charging badly (interruptions), and WiFi practically unavailable. This was an overall bad board. Too bad it had been sent out. But ok, mistakes can happen. I am forgiving. The service and friendliness of OP/ED is compensating enough!

 

Then I upgraded to a Rebirth Pandora (OP3CC, 2012-12). WiFi sucked again!!!

 

 

That meant that the efficiency/networking capabilities the Pandora was advertised for besides its gaming capabilities never were available to me. I felt disappointed. And angry, that I had to invest hours of troubleshooting even with my 3rd Pandora. Ok — we are nerds and we love tinkering — but a third time again? Christmas holidays, I wanted to finally enjoy my Pandora, my motivation to troubleshoot was close to nil. But then I felt the challenge, and I went for it! Collected empirical data and solved the puzzle! And I share this with you now! That's so great about OpenPandora: Community! And awesome battery runtime, controls, sound quality... and more...

 

 

WIFI INVESTIGATION EN DETAIL

 

I invested dozens of hours in trial'n'error already in 2011 when I got my OP1CC, but now with the meanwhile available excellent monitoring tool sysinfo, I was finally enable to also get some reliable data to back up my suppositions, now on my Rebirth Pandora (OP3GC) with SuperZaxxon 1.52 with the system upgrades up-to-date.

 

At first I did everything possible to exclude the possibility that it's a problem of my WLAN, although this was very unlikely, as all our other households devices always had excellent connections (iPhone 3, HTC Wildfire S, MacBookPro, IBM ThinkPad, visiting friends' devices). And the Pandora neither worked at my home WLAN nor in other WLANs. Nevertheless! I tried all different channels. I even measured the WiFi penetration in my whole apartment. Nothing helped or brought any insights.

 

 

Web browsing was ultra slow, practically useless. You saw the first chunk of a page, but it loaded endlessly, and never finished, so that the trigger finger itched for a reload. But also those reloads got stuck again. Only once in a few hours of browsing I was lucky to "surf on a seemingly fast wave" and received a complete page.

 

 

Then I set up a local web server wired to the WiFi router, and ensured the Pandora was the only participant of my home WiFi. I used wget to download a 1GB file, created with dd from /dev/random, to Pandora's /dev/null, so that the SD card is no factor in my test. Again it mostly stalled or stuttered at best.

Aborting and restarting brought some short time of transmission, but never for long. After a few seconds no transmission anymore. After some minutes again some short spikes, then stalling again. Restarting again and again. 

 

wifi-powersavingon-lucky-600kbs--1000mb-wget-from-wired-local-webserver--20121225-195034.png Then one lucky time it got 600 KB/sec.

And it kept it until my server accidentially went down. I could not recognize any logical pattern yet.

I tried several different scenarios, such as attempting to download right after WiFi enabling, after machine restart with auto WiFi enabled, after standby, etc... — and wether this made any difference. I got different results, but I could still not recognize a causal pattern.

 

 

I then disabled power saving. And I got steady 600-800 KB/sec immediately! And always! After I had paused for a few seconds, but also after I had paused for minutes. And regardless of the previous machine & WiFi state. WiFi was just ready for full speed all time!

 

Ok at least that worked. But still I asked myself the question:

Why is WiFi sometimes working with power saving, and sometimes not?

 

 

I did the wget test with power saving enabled. Several times. And one lucky time, it started with 70 KB/s, stayed there a while, then increased to 150 KB/sec, kept that speed a while, then reached about 600 KB/s, and then kept it. Permanently! Only a speed drop of 1-3sec every 30-90secs, but always returned back to about 600 KB/sec. Normal network variation.

 

Now it all got clear to me: If WiFi connects to a server with a stable high downlink speed and downloads a large file which thus causes a long lasting connection, and this transmission lasts long enough until reaching a certain critical point, then it reaches a stable condition with a constant proper transmission speed!

 

View attachment 5039

 

 

If the connections are of shorter nature (such as web browsing, where one page contains numerous small files, which are downloaded in parallel or sequence), or where the downlink speed is bad, that critical point is almost never reached, and power saving cuts in so aggressively, that it "kills of WiFi, before reaching its potential", cutting into its own flesh!

 

View attachment 5041

 

As a shrink would say: "Pandora's WiFi power saving algorithm has serious suicidal tendencies!"

 

It seems calibrated very badly!!!

 

I don't know the inner workings of it, but this is my guess:

The first threshold (concerning speed and/or duration) is set way to high, so that almost none of the legitimate attempts comes through to get a chance of. Power saving seems to suppress almost all attempts, although most of them are no "noise to be ignored", but rather "justified and thus relevant" transmissions!

 

 

COMMANDS USED

 

On the wired web server:




sudo dd if=/dev/random of=/path/to/htdocs/test/1000mb.bin count=1000 bs=1m

On the Pandora:



Code:
sudo iwconfig wlan0 power <on|off>

Code:
sysinfo: Set interval to 1sec (with key up/down). Watch Network tab or go to the help screen if you want to lower the CPU load. Then start logging (with "L").

Code:
wget http://your-wired-webserver.local/ -O /dev/null


Code:
sysinfo: Stop logging (with "L"). Watch appdata/sysinfo/logs and/or plot with the Pandora System Info Plot App (included in the PND).



GRAPHS:

 

Powersaving on

 

Web browsing

Was practically useless.

 

wifi-powersavingon-website-loading-never-completes--20121127-004113.png Loading never completes as WiFi croaches or stalls.

wifi-powersavingon-website-loads-complete-due-to-several-manual-reload-issueing--20121127-004523.png Only in a few moments or after several reload attempts, one gets lucky because either the page is very small or some connection luckily "made it through" the improper power saving treshhold.

 

PNDManager

 

View attachment 5041 Was practically useless. Only a few large downloads for which I triggered several reloads, once got onto the "lucky line of the WiFi power management", and then downloaded with an amazing speed.

 

Downloading large file from server with guaranteed high downlink speed

(Local server wired to WiFi router without other WiFi participants or reliably speedy download mirror site)

 

View attachment 5039 Through my research I realized that once a certain critical point of download duration and speed was reached, it then reaches a stable condition with a permanent high transmission speed. In this graph it starts with ~70 KB/sec, stays like this a while, then ~150 KB/sec for a while, then climbs to ~600 KB/sec and keeps it! Just some occasional temporal speed drops here and then, 1-3 seconds of reduced speed every 30-180secs.

 

 

Powersaving off

 

Web browsing

 

wifi-powersavingoff-webbrowsing--20121227-025056.png Every page element is loaded at full speed, the gaps inbetween are processing and requesting the new element, perfectly normal.

 

Downloading large file from server with guaranteed high downlink speed

 

No graph needed. I reach an avg of about 600 KB/sec with occasional 1-3 second drops every 30-180secs. Nice!


 

QUESTIONS:

 

  1. How can I permanently deactivate wifi-power-saving on the Pandora?
    Will any of these Linux hints work (hook in pm-utilspower.dNetworkManager)?
    Or is there something Pandora-specific to regard?
[*]Nevertheless I would like internal WiFi power saving to work. Is an improvement likely? Could my report and data help to debug?
  1. Would "USB on with an active USB-WiFi-Dongle (with power saving if possible) and internal WiFi off" be as power efficient as "USB off with internal WiFi on with proper power saving"?
[*]Is the WiFi chip&firmware better on the 1 Ghz Pandora?

FILES:

WiFi-powersaving-on-off.zip ZIP archive with numerous related sysinfo logs & plots for detailed inspection.
 

Attachments

  • WiFi-powersaving-on-off.zip
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steveway

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Fun Fact:

1. This is no news and has been known here for quite a long time.

2. There are still other things that make the wifi of many pandoras slow even with powersaving turned off. (Consider yourself lucky!)

EDIT: Also stop spamming all the old Wifi Threads with this!
 
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EvilDragon

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Powersaving might be the reason in conjunction with the router used...


My Pandora has a stable 500-800kb/s download speed with power saving enabled, both with PNDManager (heck, I even upgraded Battle of Wesnoth with it) and wget or even Android PlayStore.


No problems with webbrowsing and power saving enabled on the two units we got here...


Sure, if Wifi is generally slow (might be depending on the router used, channel settings, etc.), then these stalls might really be worked around by disabling powersaving...
 

bismuthdrummer

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I think the performance still varies greatly for the CircuitCo (original) units. I've owned two of these, and both had pretty bad performance even with power management off. I mean "bad" for 2013; of course many of us likely remember dial-up speeds, so what we have is generally sufficient regardless.

Just tested again on my CC unit and my 1 GHz: about 410 Kb/s average (480 Kb/s peak) download for the former on a good run, and about 580 Kb/s average (840 Kb/s peak) download on the latter on a good run. And the unit I sent in for upgrade had worse than 410 Kb/s average. So not quite the 500-800 you suggested for my original units, but that's a close ballpark and correct for my 1 GHz.

Power management on strangles both my units for ~200-300 Kb/s (tried multiple tests), which isn't brutal but definitely noticeable.

Perhaps I could toggle other things, but in my experience they will have little impact. More importantly, external factors *should* be ultimately irrelevant imho since I never concern myself with them for other devices (e.g. my phone or laptop at a cafe).

I agree that power management should be off by default on install, since customers are probably more forgiving for wifi that performs well even if it is greedy. The wifi can be toggled off with ease.
 
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porg

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@EvilDragon:

As described en detail, any of my 3 Pandoras were always the only troubled device in the many WiFi networks, which I attempted to use!

If the Pandora WiFi only works under some very specific environments, then it is unsuited for practical WiFi use!

Don't get my tone wrong, I am loving the Pandora! And I invest a lot of time in the community, in interaction design of some software projects, beta testing, answering some support questions, and in this case HW/SW-troubleshooting and sharing my collected data and findings with the community. So this is a very particular critique: WiFi.

And now with substantial efforts invested & considerably data provided, I hope someone takes the decency to have a look at it, and give a detailed answer to the detailed observations ("critical point" aka threshold, etc).

@steveway:

Ad 1: Give sources or quotes please.

Ad 2: I have read of HW related causes (insulating tape), and experienced one clear HW cause myself with my Pandora #2, if you read my post carefully.

To post a topic related link plus a contextualising info in a post of a similar time period is NOT spamming at all!
 

porg

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More importantly, external factors *should* be ultimately irrelevant imho since I never concern myself with them for other devices (e.g. my phone or laptop at a cafe).
This is exactly what I try to tell EvilDragon by:

If the Pandora WiFi only works under some very specific environments, then it is unsuited for practical WiFi use!
One cannot control those external factors. The device (Pandora) must adapt to them. That's the reality!
 

steveway

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Do I need to use the Forum Search for you porg? Well, I did and found a lot of old posts with this information. For example this one: http://boards.openpandora.org/index.php/topic/425-small-wifi-fix/?hl=%2Biwconfig+%2Bwlan0+%2Bpower+%2Boff#entry7261

(That's from 2010, just so you know.)

 You are pulling up old posts from September last year and post your links in there. That _is_ spamming!

Also it has been stated not long ago that the Wifi-chip was not a good choice back then, since it has so much problems.

The Pandora can't adapt to these factors because that decision has been made way in the past, we only can live with it now and try not to do the same mistake in the future with a Pandora 2.
 
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hailrazer

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I agree, there is no need to Spam the board with a link to this thread. 

Members who are having a problem with Wi-Fi will obviously be looking for threads on this matter and can come here for a look. 

I cleaned up a few of the other threads. Let's stick to this one and also now we can stay on topic :)
 
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danielo515

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So I have to accept my pandora's wifi is Absolutely useles?
As other users said, the pandora is the only device with problems in all the networks I tried, which is quite frustrating.
I'm on a hotel now, and if I want to take advantage of the wifi I have to Download the PND's with my smartphone. This is sad.

How can I turn off power saving
 

quartercast

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Porg, "sudo iwconfig wlan0 power off rate 54M" is all over these forums!

Its even in Dredd's signature afaik! :D

Edit: daniel type that into your terminal ^
 
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F_Slim

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Porg's post is not about the fact that appearently "sudo iwconfig wlan0 power off" does help (he even links to the Wiki in case you haven't noticed), but the attempt to figure out why (by doing usefull tests under well defined conditions)!

Important new result: it's probably not the power-saving itself but the agressive way it cuts down power.

I would think this is worth investigating, and not something to bash and laugh at ... especially when someone has put that much effort into the matter to finally get some meaningfull test-results :mellow:
 

quartercast

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Ah ok - apologies to porgie then :)

When I first read the topic on tapatalk maybe I missed the "more" button where all the goodies are hehehe
 

EvilDragon

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Yes, he did some good testings there but it still didn't make much sense digging out almost every Wifi Topic there is ;)

Well, that said, I think disabling powersaving is a workaround when having connection issues, but not the culprit itself.

The units I've got here (the one from me and my girlfriend) work fine without powersaving disabled, except for in some hotels (but then again, these hotels even didn't work properly with my phone...)

And I know I had units (mostly CC) where disabling powersaving didn't improve anything.

So this seems to heavy rely on the router / setup used.
 

_wb_

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I guess what we need is to reverse-engineer the crappy proprietary closed-source wifi driver binary blob so we can 1) make the Pandora even more Open Source, and 2) fix the overly aggressive power saving.

Another approach (that involves less work but yields a less clean solution) would be to write a daemon that monitors network use and automatically disables/enables power saving.
 

bismuthdrummer

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I guess what we need is to reverse-engineer the crappy proprietary closed-source wifi driver binary blob so we can 1) make the Pandora even more Open Source, and 2) fix the overly aggressive power saving.
If there were a bounty or dev fund specifically for this, I would surely pitch in. I understand that somebody needs to have the time, knowledge, and desire as well...
 

mindlord

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I can further corroborate EvilDragons assertion that it depends on the router. I have three Wifi routers: a cheap Belkin, a stock Linksys, and a Linksys with DDWRT on it. On the Belkin not only does the Pandora behave badly, but it will crash the router so it will not accept any more wifi traffic. The stock Linksys seems to work fine. The DDWRT Linksys works ok, but not as well as the stock, for some reason.

With power saving off the general behaviors are the same. I do get more speed, and a more stable connection. The Belkin still crashes though. Additionally, my Pandora appears to crash my mother-in-laws Cisco router, too.

I still have to blame the Pandora for the bad behavior. Otherwise, it wouldn't cause the Belkin to crash. I disable power saving most of the time anyways out of habit since it allows me to do light surfing on risky routers without crashing them.
 

EvilDragon

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I still have to blame the Pandora for the bad behavior. Otherwise, it wouldn't cause the Belkin to crash. I disable power saving most of the time anyways out of habit since it allows me to do light surfing on risky routers without crashing them.
Wooot, that's interesting. Sure, if it's only the Pandora doing it, it seems to be the Pandora... but it's interesting that a Wifi device can crash down a complete router.

Seems they got some bugs in there as well ;)
 

fusion_power

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I also know about the powersaving issue and have a shortcut on my Pandora Desktop to disable it for better WiFi speed. But that's not how it should be supposed to work, since it really drains battery much faster without powersaving (obviously).

Not sure if this iss a general problem of the WiFi chip or just an pure Software issue, maybwe this chip is built in other Handheld deviced with similar issues? Are things known beyond our Pandora in relationship to this Chip?
 

Binky

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