Opened 3 months ago

Closed 7 weeks ago

#5724 closed (fixed)

High cpu usage and low throughput when using BitTorrent DIR-859 A3 / Sudden WAN and LAN router communication loss on multiple builds

Reported by: Deltabongo2 Owned by:
Keywords: Cc:

Description

Router: DIR-859 A3 Build: v3.0-r31277

When downloading via BitTorrent?, throughput is low and CPU usage spikes, causing the router to crash (LAN interface can't be pinged).

Multiple "ath10k_pci 0000:00:00.0: SWBA overrun on vdev 0, skipped old beacon" are logged when the router is slowing down / about to crash.

Attached is the last block from syslog before the crash as well as the subsequent reboot.

Attachments (4)

DIR-859 A3 Crash.txt (37.8 KB) - added by Deltabongo2 3 months ago.
DIR-859 Top BitTorrent Crash.jpg (142.4 KB) - added by Deltabongo2 3 months ago.
DIR-859 Top Direct Download Full Speed.jpg (142.3 KB) - added by Deltabongo2 3 months ago.
DIR-859 Top Direct Download Crash.jpg (139.5 KB) - added by Deltabongo2 2 months ago.

Download all attachments as: .zip

Change History (16)

Changed 3 months ago by Deltabongo2

comment:1 Changed 3 months ago by tatsuya46

check memory usage when its about to crash, and results of "top" in ssh/telnet, im assuming it should be sirq thats maxing the cpu.. and "maximum ports" under ip filter settings are set to what?

Last edited 3 months ago by tatsuya46 (previous) (diff)

Changed 3 months ago by Deltabongo2

Changed 3 months ago by Deltabongo2

comment:2 Changed 3 months ago by Deltabongo2

The first screen grab I uploaded shows the status in top when the router crashes during a BitTorrent? download. "sirq" will increase or decrease depending on the throughput of the download in near realtime. When the server slows down, it's "sys" that spikes (sometimes over 90%). Several processes (ie, hostapd, resetbutton, watchdog etc...) will consume a high percentage of CPU cycles when the router either bogs down or crashes.

The second screen grab shows the direct download of a large .iso file. "sirq" stays in the 22-25% range while maxing out my 50Mb connection. Load average stays very low (the 5 and 15 minutes load averages are higher because the router had just been rebooted after the BitTorrent? download crash).

IP Filter Settings TCP Congestion Control: westwood Maximum Ports: 4096 TCP Timeout: 3600 UDP Timeout: 120

Version 0, edited 3 months ago by Deltabongo2 (next)

comment:3 Changed 3 months ago by Deltabongo2

I did more testing today and have found that disabling the 5Ghz radio seems to fix the high CPU spikes and high memory usage. Any idea why?

comment:4 Changed 3 months ago by Deltabongo2

I have done further testing concerning this issue on build r31544 and the issue persists when the 5Ghz radio is enabled.

Enabling the 5Ghz radio (QCA9880) consumes around 15MB of RAM on its own (Router has 64MB RAM total and about 61.6MB usable). I'm wondering if this may not be leaving enough free memory for the router to keep running under heavy load. With both the 2.4 and 5GHz radios enabled, I've seen free memory drop to around 5MB before the router crashes.

If I disable the 5GHz radio, free memory stays in the 26-30 MB range and the router runs fine.

Is there a potential fix for the amount of memory the QCA9880 chip consumes (or is there a memory leak?), or is this router simply lacking enough RAM to run this radio properly?

Last edited 3 months ago by Deltabongo2 (previous) (diff)

Changed 2 months ago by Deltabongo2

comment:5 Changed 2 months ago by Deltabongo2

The "DIR-859 Top Direct Download Crash.jpg" screen capture shows the status of the router when it crashed while doing a direct download at full speed (~65Mb). Prior to this last Top screen refresh sirq had been much lower (~20-25%).

When it crashes, the following is observed: Wifi and Lan lights on router still blinking, no internet connection (wired or wireless) and can't ping router LAN IP. Wireless clients are still connected to the router (2.4Ghz, the 5Ghz radio is disabled). Reboot the router and it's ok for a while until it is placed under sudden, heavy load.

I can't seem to find a build that doesn't have this issue.

Last edited 2 months ago by Deltabongo2 (previous) (diff)

comment:6 Changed 2 months ago by Deltabongo2

  • Summary changed from High cpu usage and low throughput when using BitTorrent DIR-859 A3 r31277 to High cpu usage and low throughput when using BitTorrent DIR-859 A3 r31277 / Sudden WAN and LAN router communication loss

comment:7 Changed 2 months ago by Deltabongo2

  • Resolution set to fixed
  • Status changed from new to closed

comment:8 Changed 2 months ago by Deltabongo2

  • Resolution fixed deleted
  • Status changed from closed to reopened

Any ideas?

comment:9 Changed 2 months ago by Deltabongo2

  • Summary changed from High cpu usage and low throughput when using BitTorrent DIR-859 A3 r31277 / Sudden WAN and LAN router communication loss to High cpu usage and low throughput when using BitTorrent DIR-859 A3 / Sudden WAN and LAN router communication loss on multiple builds

comment:10 Changed 2 months ago by Deltabongo2

Have observed the issue on builds 30342, 31277, 31544, 31571

comment:11 Changed 7 weeks ago by Deltabongo2

Issue may have been due to having the router use PPOE instead of a static IP for the WAN connection. Uptime of 20 days with 31544 since setting the WAN IP of the router to a static IP in the ISP modem's subnet. Have just flashed 31791, ran some tests and router appears stable.

comment:12 Changed 7 weeks ago by Deltabongo2

  • Resolution set to fixed
  • Status changed from reopened to closed

Issue appears fixed by setting router WAN IP to static in the ISP modem's subnet vs. using PPPOE.

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