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Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 2:07 am
by rkruz3
When downloading over a wired 1Gb LAN, using WIndows 10, the torrent speed will drop to 0 at very regular intervals. See the attached speed graph.
Is this something I can correct on my end?
Or is this a behavior of the torrent system out of my control?
Thank you!
qbitspeed.jpg
qbitspeed.jpg (78.2 KiB) Viewed 7212 times

Re: Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 2:05 pm
by unseen19
Hi, what' your QBT version? May be something related to 4.4.0 but nothing shows up recently related to such.
I'll so consider the lack of bug and consider 2 options:

- Enough seeders for this torrent? The speed is around 10MB/s at best so except if you put a limit on the D/L speed, it's not much
- Disk speed issue? It may be some swap flush, check in the task manager the destination disk utilization. Any similar pattern?
(of course it's worst if you use an USB disk)

Re: Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 5:08 pm
by taulen
In 4.4.0 it seems its downloading for x amount time, and then flushing a cache (swap flushing as you are calling it) or something, while this is a different behavior than on 4.3.9 or previous.
Seeing the same as the user above, but a much bigger extent, as downloading with 1gbit.
While its flushing the cache it stops downloading. This is not happening on 4.3.9, I re-installed 4.3.9 and its back to normal, so something changed.

Re: Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 5:13 pm
by taulen

Re: Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 5:24 pm
by rkruz3
Thank you for the insight!
This is Qbittorrent version 4.4, Windows 10, saving the file to a Synology NAS over a 1Gb LAN.
I used to see a nice contiguous data flow, I think before the upgrade, now I get these regularly space data drops. The download completes but I have not seen these drops before.

Regarding Seeders, the first chart attached shows 23/61 and for comparison, the 2nd chart shows 150/8400.
Both seem to exhibit the regularly spaced data dropout.
Looking at the destination NAS performance, I dont see anything that comes close to a limit such as Disk and Network Utilization. Probably in the <10% range.
I have no limits checked in Qbittorrent, up or down, it's fully open both ways and most settings are at default.
In the best conditions, I can get up to about 16 MB/s downloads with my Internet Service Provider. The VPN is PIA.

The first chart is the same torrent as the first post again this morning.
torrent drops.jpg
torrent drops.jpg (106.17 KiB) Viewed 7178 times
The 2nd chart is a new torrent with 8400 Seeds.
torrent drops.jpg
torrent drops.jpg (106.17 KiB) Viewed 7178 times

Re: Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 6:00 pm
by rkruz3
Yes its version 4.4 that is the issue.
I installed version 4.3.9 and now the download is contiguous without the regular drop outs.
Here is a download graph of the exact torrent that was first posted but now using version 4.3.9.
Note it has no regular dropouts.
I hope this is helpful.
thanks for the tips!
qbit download.jpg
qbit download.jpg (102.19 KiB) Viewed 7168 times

Re: Speed drops to 0 at Regular Intervals

Posted: Tue Jan 11, 2022 6:16 pm
by Nemo
I have commented to the devs to take an another look at it within libtorrent itself:

https://github.com/qbittorrent/qBittorr ... 1010233125

Edit:
Also at libtorrent Github page:
https://github.com/arvidn/libtorrent/issues/6522

Re: Speed drops to 0 at Regular Intervals

Posted: Sun Jan 16, 2022 6:23 pm
by ItsMe
First of all, sorry for my English.

I have same speed graph and I have very low pc.
But only happens for me in the beginning of the tasks and etc.:
  1. graph is healthy >> for example I run Firefox browser >> speed drops 10 MB/s to 20 KB/s or 0 immediately. >> speed graph so much spikes down and up >> after some time like 30 sec. in loading previous session tabs, Firefox loaded and it is almost ready to use >> graph is normal.
  2. graph is healthy >> I move any torrents using qBittorrent from current drive to another drive >> speed drops regular intervals >> still moving torrents >> still speed drops regularly >> moving finished >> graph is normal
  3. and same regular drops when CPU usage high
  4. and when running mkinitcpio after the every Linux kernel binary update(for my understanding: when CPU throttling. I see 11 when I look one minute CPU load average)
v4.4.0 from community repo & Arch Linux

Re: Speed drops to 0 at Regular Intervals

Posted: Sun Jan 16, 2022 6:27 pm
by rkruz3
its a problem with V4.4. V3.3.9 works great

Re: Speed drops to 0 at Regular Intervals

Posted: Sun Jan 16, 2022 6:40 pm
by ItsMe
rkruz3 wrote: Sun Jan 16, 2022 6:27 pm its a problem with V4.4. V3.3.9 works great
Thanks I will use V3.3.9 for temporarily.

When I see this page today I was so happy because before was never found this related issue in github, reddit or google. Especially with the same/similar spike graph :D

Re: Speed drops to 0 at Regular Intervals

Posted: Sun Jan 16, 2022 6:49 pm
by rkruz3
your welcome, I think thats recommended until a patch is updated. There is nothing wrong with 3.3.9 as far as I use it in its simplest function.

Re: Speed drops to 0 at Regular Intervals

Posted: Sat Jan 22, 2022 10:01 pm
by Nemo
If you mean v4.3.9 then yes, use that till v4.4.1.