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Even single user, bufferbloat matters. Windows update will kill your
Skype call. Without large size aggregates the necessary physical
layer per packet overheads caused by the RF medium kill your
efficiency and performance. Fairness between users is another issue
as well.<br>
<br>
Simon<br>
<br>
<div class="moz-cite-prefix">On 5/17/2015 8:30 PM, <a class="moz-txt-link-abbreviated" href="mailto:dpreed@reed.com">dpreed@reed.com</a>
wrote:<br>
</div>
<blockquote cite="mid:1431919815.385726792@apps.rackspace.com"
type="cite"><font face="times new roman" size="2">
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;">What's your
definition of 802.11 performing well? Just curious.
Maximizing throughput at all costs or maintaing minimal
latency for multiple users sharing an access point?<br>
<br>
Of course, if all you are doing is trying to do point-to-point
outdoor links using 802.11 gear, the issue is different -
similar to "dallying" to piggyback acks in TCP, which is great
when you have two dimensional flows, but lousy if each packet
has a latency requirement that is small.</p>
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;"> </p>
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;">To me this is hardly
so obvious. Maximizing packet sizes is actually
counterproductive for many end-to-end requirements. But of
course for "hot rod benchmarkers" applications don't matter at
all - just the link performance numbers.</p>
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;"> </p>
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;">One important use of
networking is multiplexing multiple users. Otherwise,
bufferbloat would never matter.</p>
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;"> </p>
<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;">Which is why I think
actual numbers rather than "hand waving claims" matter.</p>
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<p style="margin:0;padding:0;font-family: 'times new roman';
font-size: 10pt; word-wrap: break-word;"><br>
<br>
On Friday, May 15, 2015 10:36am, "Simon Barber"
<a class="moz-txt-link-rfc2396E" href="mailto:simon@superduper.net"><simon@superduper.net></a> said:<br>
<br>
</p>
<div id="SafeStyles1431919447">
<div style="color: black;">
<div style="color: black;">
<p style="margin:0;padding:0;margin: 0 0 1em 0; color:
black;">One question about TCP small queues (which I
don't think is a good solution to the problem). For
802.11 to be able to perform well it needs to form
maximum size aggregates. This means that it needs to
maintain a minimum queue size of at least 64 packets,
and sometimes more. Will TCP small queues prevent this?</p>
<p style="margin:0;padding:0;margin: 0 0 1em 0; color:
black;">Simon</p>
<p style="margin:0;padding:0;margin: 0 0 1em 0; color:
black;">Sent with AquaMail for Android<br>
<a moz-do-not-send="true"
href="http://www.aqua-mail.com">http://www.aqua-mail.com</a></p>
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<div style="color: black;">
<p style="margin:0;padding:0;color: black; font-size:
10pt; font-family: Arial, sans-serif; margin: 10pt 0;">On
May 15, 2015 6:44:21 AM Jim Gettys
<a class="moz-txt-link-rfc2396E" href="mailto:jg@freedesktop.org"><jg@freedesktop.org></a> wrote:</p>
<blockquote class="gmail_quote" style="margin: 0 0 0
0.75ex; border-left: 1px solid #808080; padding-left:
0.75ex;">
<div dir="ltr">
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, May 15, 2015 at
9:09 AM, Bill Ver Steeg (versteb) <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:versteb@cisco.com"
target="_blank">versteb@cisco.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0 0
0 .8ex; border-left: 1px #ccc solid;
padding-left: 1ex;">Lars-<br>
<br>
You make some good points. It boils down to the
fact that there are several things that you can
measure, and they mean different things.<br>
<span class="HOEnZb"><span style="color:
#888888;"><br>
Bvs<br>
</span></span>
<div class="HOEnZb">
<div class="h5"><br>
<br>
-----Original Message-----<br>
From: Eggert, Lars [mailto:<a
moz-do-not-send="true"
href="mailto:lars@netapp.com">lars@netapp.com</a>]<br>
Sent: Friday, May 15, 2015 8:44 AM<br>
To: Bill Ver Steeg (versteb)<br>
Cc: Aaron Wood; <a moz-do-not-send="true"
href="mailto:cake@lists.bufferbloat.net">cake@lists.bufferbloat.net</a>;
Klatsky, Carl; <a moz-do-not-send="true"
href="mailto:cerowrt-devel@lists.bufferbloat.net">cerowrt-devel@lists.bufferbloat.net</a>;
bloat<br>
Subject: Re: [Bloat] [Cerowrt-devel]
heisenbug: dslreports 16 flow test vs
cablemodems<br>
<br>
<br>
I disagree. You can use them to establish a
lower bound on the delay an application over
TCP will see, but not get an accurate
estimate of that (because socket buffers are
not included in the measurement.) And you
rely on the network to not prioritize
ICMP/UDP but otherwise leave it in the same
queues.</div>
</div>
</blockquote>
<div>
<div class="gmail_default" style="font-size:
small; display: inline;">On recent versions
of Linux and Mac, you can get most of the
socket buffers to "go away". I forget the
socket option offhand.</div>
</div>
<div>
<div class="gmail_default" style="font-size:
small;">And TCP small queues in Linux means
that Linux no longer gratuitously generates
packets just to dump them into the queue
discipline system where they will rot.</div>
<div class="gmail_default" style="font-size:
small;">How accurate this now can be is still
an interesting question: but has clearly
improved the situation a lot over 3-4 years
ago.</div>
</div>
<blockquote class="gmail_quote" style="margin: 0 0
0 .8ex; border-left: 1px #ccc solid;
padding-left: 1ex;">
<div class="HOEnZb">
<div class="h5"><br>
> If you can instrument TCP in the kernel
to make instantaneous RTT available to the
application, that might work. I am not sure
how you would roll that out in a timely
manner, though.<br>
<br>
</div>
</div>
</blockquote>
<div class="gmail_default" style="font-size:
small;">Well, the sooner one starts, the sooner
it gets deployed.</div>
<div class="gmail_default" style="font-size:
small;">Jim</div>
</div>
</div>
</div>
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