Specific TCP/IP Settings for Torrents?

[quantar]

Hi there,
I traced a bandwidth problem for a long time until I finally could figure out the type of cause.
After a couple of minutes the torrent speed decreases massively (20MB/s -- 1MB/s). Rebooting the router helps, but again just for a couple of minutes.
The problem disappeared after I more or less randomly increased the TCP/IP values. Now I try to figure out what the relevant variable(s) is/are and what the maximum value.
Do you have any suggestions for the settings here?

Edit: It is a Asus N66U running latest Merlin with 400Mbit/s down and 25Mbit/s up
Edit2: The problem reappeared, after about 1 hour traffic broke in again, so adding just one "0" seems not enough.

thanks
quan

 

[joegreat]

I recall that long, long time ago (~2013) I setup-up Torrent-ing on my N66U and I recalled setting some TCP buffers (good that I still had a backup of the old config):

Add this lines to the init-start user script in /jffs/scripts and make it executable:
#!/bin/sh
# When uTorrent transport protocol is enabled give transmission the
# added memory to 5MB receive and 1.5MB send
echo 5242880 > /proc/sys/net/core/rmem_max
echo 1572864 > /proc/sys/net/core/wmem_max

Additionally it could be good to avoid buffer-bloat (not sure it will help) - remember to use the correct network devices from the N66U (get them from ifconfig) - also to be added into the init-start script:
# for buffer-bloat are a lot of fixes coming up but the current method for
# reducing it for linux routers is to reduce the buffer size.
# This router has a 1000 packet buffer and I just want to reduce that to 100
/sbin/ifconfig <<WAN>> txqueuelen 100
/sbin/ifconfig <<LAN>> txqueuelen 100
# WLANs
/sbin/ifconfig <<2.4GWLAN>> txqueuelen 16
/sbin/ifconfig <<5GWLAN>> txqueuelen 16

In general you need to be patient with your small MIPS CPU based N66U: It's not that fast in processing Torrents (especially in read/write to the disk).

Even my AC87U with an overclocked ARM CPU is struggling to handle the disk fast enough - the max rates I get are 15 MBit down with 7.5 MBit up in parallel - again it's due the disk handling as the router CPU has no help from DMA or a nice 6 Gbit SATA sub-systems.

I would guess, that you have to expect the limits of your router around 50% of my ones...