From: Grant <emailgrant@gmail.com>
To: Gentoo mailing list <gentoo-user@lists.gentoo.org>
Subject: [gentoo-user] Re: TCP Queuing problem
Date: Tue, 20 Sep 2016 06:08:31 -0700 [thread overview]
Message-ID: <CAN0CFw0yubM+_K4r_U4766CtrhYGz=RNr4MWtb4UGG8F6d0xhg@mail.gmail.com> (raw)
In-Reply-To: <CAN0CFw1KXZgx_PFDHhw9PsHADtQTOwcJawddOc9NtNsY3qDbCw@mail.gmail.com>
>>>> My web server's response time for http requests skyrockets every
>>>> weekday between about 9am and 5pm. I've gone over my munin graphs and
>>>> the only one that really correlates well with the slowdown is "TCP
>>>> Queuing". It looks like I normally have about 400 packets per second
>>>> graphed as "direct copy from queue" in munin throughout the day, but 2
>>>> to 3.5 times that many are periodically graphed during work hours. I
>>>> don't see the same pattern at all from the graph of all traffic on my
>>>> network interface which actually peaks over the weekend. TCP Queuing
>>>> doesn't rise above 400 packets per second all weekend. This is
>>>> consistent week after week.
>>>>
>>>> My two employees come into work during the hours in question, and they
>>>> certainly make frequent requests of the web server while at work, but
>>>> if their volume of requests were the cause of the problem then that
>>>> would be reflected in the graph of web server requests but it is not.
>>>> I do run a small MTU on the systems at work due to the config of the
>>>> modem/router we have there.
>>>>
>>>> Is this a recognizable problem to anyone?
>>>
>>>
>>> I'm in the midst of this. Are there certain attacks I should check for?
>>
>>
>> It looks like the TCP Queuing spike itself was due to imapproxy which
>> I've now disabled. I'll post more info as I gather it.
>
>
> imapproxy was clearly affecting the TCP Queuing graph in munin but I
> still ended up with a massive TCP Queuing spike today and
> corresponding http response time issues long after I disabled
> imapproxy. Graph attached. I'm puzzled.
I just remembered that our AT&T modem/router does not respond to
pings. My solution is to move PPPoE off of that device and onto my
Gentoo router so that pings pass through the AT&T device to the Gentoo
router but I haven't done that yet as I want to be on-site for it.
Could that behavior somehow be contributing to this problem? There
does seem to be a clear correlation between user activity at that
location and the bad server behavior.
- Grant
next prev parent reply other threads:[~2016-09-20 13:08 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-17 21:13 [gentoo-user] TCP Queuing problem Grant
2016-09-19 17:23 ` [gentoo-user] " Grant
2016-09-19 21:25 ` Grant
2016-09-20 0:38 ` Grant
2016-09-20 13:08 ` Grant [this message]
2016-09-21 4:01 ` Kai Krakow
2016-09-21 14:30 ` Grant
2016-09-21 19:29 ` Kai Krakow
2016-09-21 19:37 ` Grant
2016-09-21 20:06 ` Kai Krakow
2016-09-21 20:28 ` Kai Krakow
2016-09-21 19:41 ` Kai Krakow
2016-09-21 19:53 ` Grant
2016-09-21 20:18 ` Kai Krakow
2016-09-21 20:47 ` Grant
2016-09-21 21:44 ` Michael Mol
2016-09-22 0:30 ` Grant
2016-09-22 7:06 ` Kai Krakow
2016-09-25 0:25 ` Grant
2016-10-01 9:57 ` Grant
2016-09-20 13:50 ` J. Roeleveld
2016-09-20 14:53 ` Grant
2016-09-20 18:06 ` J. Roeleveld
2016-09-20 19:52 ` Grant
2016-09-20 20:19 ` Alarig Le Lay
2016-09-22 16:58 ` Volker Armin Hemmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAN0CFw0yubM+_K4r_U4766CtrhYGz=RNr4MWtb4UGG8F6d0xhg@mail.gmail.com' \
--to=emailgrant@gmail.com \
--cc=gentoo-user@lists.gentoo.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox