<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>
<!--WM_COMPOSE_SIGNATURE_START--><!--WM_COMPOSE_SIGNATURE_END-->
<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" <simon@superduper.net> 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 href="http://www.aqua-mail.com">http://www.aqua-mail.com</a></p>
</div>
<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 <jg@freedesktop.org> 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 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 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 href="mailto:cake@lists.bufferbloat.net">cake@lists.bufferbloat.net</a>; Klatsky, Carl; <a 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>
_______________________________________________<br /> Bloat mailing list<br /> Bloat@lists.bufferbloat.net<br /><a class="aqm-autolink aqm-autowrap" href="https://lists.bufferbloat.net/listinfo/bloat">https://lists.bufferbloat.net/listinfo/bloat</a><br /><br /></blockquote>
</div>
</div>
</div></font>