<div class="gmail_quote"><div>Firstly, I can confirm uploading to Google Drive saturates my upload (I checked the outgoing rate in the router) and also tried Dropbox and got the same result. <br><br>Anyway, performing an upload with Windows 7 and then pinging the remote router with windows XP, added 50ms to the "unbloated" 20ms roundtrip times. So the lowest "most represented" RTT numbers I was getting were around 70ms, the worst well over 100ms.<br>
I said "most represented" in the previous sentence, as there was also a significant delay variance ("jitter") in the RTT's. The RTT's regularly dived under 70ms, sometimes even hitting an odd 30ms. The was also a large swing in the other direction with regular ventures to 110-120ms. Needless to say, the balance of those ventures tilted more towards the higher numbers. <br>
<br>So Windows 7, being more modern definitely induces more bufferbloat (thanks to TCP window scaling:)). I'll be repeating this when running Wireshark as it slipped my mind to fire it up. <br><br>As a sidenote to the above:<br>
I still don't see how an AQM-algorithm will combat the buffering in drivers and hardware (actually, are the issues pertaining to "drivers" and "hardware' distinct or referring to the same?). I understand that feeding less packets to a device will prevent the hardware buffer from filling up as fast as without AQM, but we cannot actually influence its (the HW buffer) size, can we? If so, it can still introduce a bottleneck that cannot be prevented...<br>
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<div class="gmail_quote"><div class="im">On Sat, Feb 9, 2013 at 2:06 PM, Forums1000 <span dir="ltr"><<a href="mailto:forums1000@gmail.com" target="_blank">forums1000@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div>Excellent information. So an AQM-algorithm will sort things on the OS
level of the router and should make things considerably better. However,
from reading around on the matter, it seems drivers for the network
device and the hardware itself also contain buffers. Since, Dave (and
respect for that) is developing CeroWRT, is there anything that can be
done about that? Do we have any idea on how severe the buffering in
drivers and hardware is?<br>
<br></div></div></blockquote></div><div><br>In linux, it's got a lot better in the past 2 years. Work continues.<br><br>I have some data on OSX now, and some on windows, but not a lot.<br><br>In APs, routers, and switches, it's not looking very good.<br>
<br><br>However I note that the second biggest place we see the issue is on the edge home gateways, dslams, cable head-ends, and many of those use software rate limiting, which generally has 1 buffer or less native to it, and the underlying buffering doesn't matter. <br>
<br>(then on top of the software rate limiters are big fat dumb drop tails queues. currently. sigh)<br><br><br> </div><div class="im"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<div>A little test I just performed using Windows XP now, indeed shows that Netalyzr is showing me a worst case scenario:<br><br></div></div></blockquote></div><div><br>Meh. Try something with window scaling. Or, try a netanalyzer test from some other machine at the same time you do this one.<br>
<br></div><div class="im"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div>-
a continuous ping (1 ping per second) between 2 routers under my
control has an RTT of 20ms (give or take). The remote router I'm pinging
sits pretty much idle and has nothing better to do than answering the
ping. <br>
- uploading a large file to Google drive (thereby saturating my uplink
bandwidth) adds +-10ms of additional latency.</div></div></blockquote></div><div><br>I think this is an invalid assumption without actually measuring your transfer rate to the the gdrive. It would not surprise me if their TCP was pretty sensitive to latency swings, however, they are very on top of the bufferbloat issue.<br>
<br>Wouldn't mind a packet capture of that upload while doing the above test.<br><br> <br></div><div class="im"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>
<div> Sure it varies a bit
between 20 and 30ms and goes to 35ms or even 40ms regularly. Moreover,
every now and then I get a spike to 70-80ms but that spike never lasts
more than 3 pings. <br>
<br>All in all considerably lower bloat than the 550ms Netalyzr is
indicating. In order to mimic the worst case scenario, I'd have to
transfer using UDP then?
</div></div></blockquote></div><div><br>Just run a more modern OS....<br> <br></div><div class="im"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>_______________________________________________<br>
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<br></blockquote></div></div><div class="HOEnZb"><div class="h5"><br><br clear="all"><br>-- <br>Dave Täht<br><br>Fixing bufferbloat with cerowrt: <a href="http://www.teklibre.com/cerowrt/subscribe.html" target="_blank">http://www.teklibre.com/cerowrt/subscribe.html</a>
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