<font face="arial" size="2"><p style="margin:0;padding:0;">Just to clarify, the way Netalyzr attempts to measure "uplink buffering" may not actually measure queue length. It just spews UDP packets at the target, and measures sender-receiver packet delay at the maximum load it can generate. So it's making certain assumptions about the location and FIFO nature of the "bottleneck queue" when it calculates that.</p>
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<p style="margin:0;padding:0;">I don't think this is good news that you are reproting.</p>
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<p style="margin:0;padding:0;">Assuming codel is measuring "sojourn time" and controlling it properly, you should not see 2.8 *seconds* of UDP queueing delay on the uplink - packets should be being dropped to keep that delay down to under 10 milliseconds.</p>
<p style="margin:0;padding:0;">I have no idea how that jibes with low ping times, unless you are getting the ICMP packets spoofed.</p>
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<p style="margin:0;padding:0;">-----Original Message-----<br />From: "Sebastian Moeller" <moeller0@gmx.de><br />Sent: Wednesday, August 15, 2012 1:23pm<br />To: "Dave Taht" <dave.taht@gmail.com><br />Cc: cerowrt-devel@lists.bufferbloat.net<br />Subject: Re: [Cerowrt-devel] cerowrt 3.3.8-17 is released<br /><br /></p>
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<p style="margin:0;padding:0;">Hi Dave,<br /><br />great work, as always I upgraded my production router to the latest and greatest (since I only have one router…). And it works quite well for normal usage…<br />Netalyzr reports around 2800ms seconds of uplink buffering, yet saturating the uplink does not affect ping times to a remote target noticeably, basically the same as for all codellized ceo versions I tested so far...<br /><br />Some notes and a question:<br />I noticed that even given plenty of swap space (1GB on a usb stick), using http://broadband.mpi-sws.org/residential/ to exercise UDP stress (on the uplink I assume) I can easily produce (I run the test from a macosx via 5GHz wireless over 1.5 yards):<br />Aug 15 01:16:29 nacktmulle kern.err kernel: [175395.132812] ath: skbuff alloc of size 1926 failed<br />(and plenty of those…). <br />What then happens is that the OOM killer will aim for bind (reasonable since it is the largest single process) and kill it. When I try to restart bind by:<br />root@nacktmulle:~# /etc/rc.d/S47namedprep start<br />root@nacktmulle:~# /etc/rc.d/S48named restart<br />Stopping isc-bind<br /> /etc/chroot/named//var/run/named/named.pid not found, trying brute force <br />killall: named: no process killed<br />Kicking isc-bind in xinetd<br />rndc: connect failed: 127.0.0.1#953: connection refused<br />And bind does not start again and the router becomes less than useful. Now I assume I am doing something wrong, but what, if you have any idea how to solve this short of a reboot of the router (my current method) I would be happy to learn<br /><br /><br /><br />best regards<br /> sebastian<br /><br />On Aug 12, 2012, at 11:08 PM, Dave Taht wrote:<br /><br />> I'm too tired to write up a full set of release notes, but I've been<br />> testing it all day,<br />> and it looks better than -10 and certainly better than -11, but I won't know<br />> until some more folk sit down and test it, so here it is.<br />> <br />> http://huchra.bufferbloat.net/~cero1/3.3/3.3.8-17/<br />> <br />> fresh merge with openwrt, fix to a bind CVE, fixes for 6in4 and quagga<br />> routing problems,<br />> and a few tweaks to fq_codel setup that might make voip better.<br />> <br />> Go forth and break things!<br />> <br />> In other news:<br />> <br />> Van Jacobson gave a great talk about bufferbloat, BQL, codel, and fq_codel<br />> at last week's ietf meeting. Well worth watching. At the end he outlines<br />> the deployment problems in particular.<br />> <br />> http://recordings.conf.meetecho.com/Recordings/watch.jsp?recording=IETF84_TSVAREA&chapter=part_3<br />> <br />> Far more interesting than this email!<br />> <br />> <br />> -- <br />> Dave Täht<br />> http://www.bufferbloat.net/projects/cerowrt/wiki - "3.3.8-17 is out<br />> with fq_codel!"<br />> _______________________________________________<br />> Cerowrt-devel mailing list<br />> Cerowrt-devel@lists.bufferbloat.net<br />> https://lists.bufferbloat.net/listinfo/cerowrt-devel<br /><br />_______________________________________________<br />Cerowrt-devel mailing list<br />Cerowrt-devel@lists.bufferbloat.net<br />https://lists.bufferbloat.net/listinfo/cerowrt-devel</p>
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