Re: Throughput riddle
On Sun, 20 Mar 2016 21:49:43 -0700
David Christensen <dpchrist@holgerdanske.com> wrote:
> On 03/20/2016 07:10 PM, Celejar wrote:
> > Laptop:
> >
> > RX packets:922215 errors:0 dropped:1967 overruns:0 frame:0
> > TX packets:1186319 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:1000
> > RX bytes:724785210 (691.2 MiB) TX bytes:1311193642 (1.2 GiB)
> >
> > NAS:
> >
> > RX packets:509256 errors:0 dropped:3 overruns:0 frame:0
> > TX packets:234641 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:1000
> > RX bytes:767110212 (731.5 MiB) TX bytes:16498728 (15.7 MiB)
> > Interrupt:87
> >
> >
> > Router (wireless interface):
> >
> > RX packets:1474219 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:1571154 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:1000
> > RX bytes:994970603 (948.8 MiB) TX bytes:1544655324 (1.4 GiB)
>
> Assuming:
>
> 1. The configuration is:
>
> laptop - WiFi - router - Cat 5 - NAS
Yes, generally. [As per my original message, I occasionally connect the
laptop to the router with ethernet cable for testing or other purposes.]
> 2. You did a cold boot on everything.
I did not.
> 3. You ran iperf from the laptop to the NAS.
Yes.
> 4. You ran iperf from the NAS to the laptop.
No.
> Ideas:
>
> 1. I assume the dropped RX statistic means that received packets were
> malformed, and not that they were dropped by a firewall rule (?).
>
> 2. The laptop WiFi interface dropping 1967 packets while the router
> WiFi interface dropping zero leads me to think there's a problem that
> only affects the laptop receiver. Perhaps you need turn up the
> transmitter power in the router (?).
>
> 3. I don't understand why the NAS dropped 3 packets. A wired
> connection should drop zero. Maybe it's the Cat 5 cable. Perhaps you
> need a Cat 5E.
>
> 4. The laptop TX bytes (1.2 GiB) and NAS RX bytes (731.5 MiB) do not
> correlate well.
Why would they match? The laptop transmits lots of other stuff than
iperf and backup traffic to the NAS.
> 5. The NAS TX bytes (15.7 MiB) and laptop RX bytes (691.2 MiB) do not
> correlate well.
Again, why would they match? The laptop receives lots of stuff
unrelated to the NAS.
> 6. Information for the router wired interface is missing.
> Please try another run per my assumptions, above. Revise and re-post
> assumptions as necessary. Post new ifconfig, iwconfig, dmesg, and
> anything else that looks like a clue.
[Before testing:]
Laptop:
ifconfig
RX packets:26691 errors:0 dropped:98 overruns:0 frame:0
TX packets:16051 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:30347357 (28.9 MiB) TX bytes:2245418 (2.1 MiB)
iwconfig
Link Quality=67/70 Signal level=-43 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:3577 Invalid misc:417 Missed beacon:0
Router (wlan0):
RX packets:26691 errors:0 dropped:98 overruns:0 frame:0
TX packets:16051 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:30347357 (28.9 MiB) TX bytes:2245418 (2.1 MiB)
Router (eth0):
RX packets:1612778 errors:0 dropped:0 overruns:4594 frame:0
TX packets:1732474 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:439536079 (419.1 MiB) TX bytes:1175937292 (1.0 GiB)
Interrupt:4
NAS:
RX packets:552082 errors:0 dropped:36 overruns:0 frame:0
TX packets:252654 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:823241120 (785.1 MiB) TX bytes:18133067 (17.2 MiB)
Interrupt:87
iperf:
laptop -> NAS: 14.8/20.6/24.2
NAS -> laptop: 53.9/65.6/67.3
Hm, I never realized this - I'm getting 2-4 times the throughput when
reversing the direction!
laptop -> router: 8.74/10.2/11.4
router -> laptop: 53.4/56.2/57.1
Wow, 5-8 times the throughput when reversing! Thanks for the suggestion
to reverse the tests - I really should have tried that on my own.
Any idea what this means?
[After testing:]
laptop:
ifconfig
RX packets:434822 errors:0 dropped:115 overruns:0 frame:0
TX packets:291397 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen
iwconfig
Link Quality=60/70 Signal level=-50 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:233699 Invalid misc:1488 Missed
beacon:0
router (wlan0):
ifconfig
RX packets:3983487 errors:0 dropped:0 overruns:0 frame:0
TX packets:5478517 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1390191564 (1.2 GiB) TX bytes:2503989443 (2.3 GiB)
router (eth0):
RX packets:1861402 errors:0 dropped:0 overruns:4594 frame:0
TX packets:1908654 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:774551024 (738.6 MiB) TX bytes:1280163068 (1.1 GiB)
Interrupt:4
NAS
ifconfig
RX packets:727563 errors:0 dropped:52 overruns:0 frame:0
TX packets:500646 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:927305181 (884.3 MiB) TX bytes:351977275 (335.6 MiB)
Interrupt:87
Celejar
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