AC66U B1 slow ftp, high cpu

[lawl]

Hello,

When I try to upload a file to ftp, I get 1-2Mb/s and both cores of the CPU tank at 100% also it uses most of the memory. The usb stick is formated as EXT4 (I tried 2 and 3 version and nothing changed). The upload freezes for a second and then start again and so on every 5-6 seconds.
I am using Asuswrt-Merlin 360.68.

What can I do?

 

[ColinTaylor]

What is the CPU usage before you start the file transfer? Try logging onto the router with SSH and running top to see what process is using the CPU.

Do you have any other processes running that constantly access the USB drive like the media server or torrents?

 

[lawl]

What is the CPU usage before you start the file transfer? Try logging onto the router with SSH and running top to see what process is using the CPU.

Do you have any other processes running that constantly access the USB drive like the media server or torrents?

The top 2 processes are vsftpd and ksoftirqd. Before the file transfer, the cpu is barely reaching 5%. And I don't have any other processes that are trying to access the USB drive. I have disabled SAMBA and I don't have any torrent client installed.

 

[ColinTaylor]

I can't think why it should be so slow/cpu-intensive. Are you trying to transfer 100's of small files? Is it the same for reading and writing? Have you tried using a different FTP client?

 

[lawl]

I am queuing multiple 200Mb files but the client (FileZilla) uploads them one at a time. I have also tried using TotalCommander and Explorer with the same result. The strangest part is that mini freeze every 5 seconds, I cannot understand where it comes from.

Edit: The download seems to work fine. I get about 20Mb/s and there are no mini freezes.

 

[ColinTaylor]

I've just tried uploading a 200MB file here and got ~7MB/s using Filezilla. The maximum write speed of my USB flash drive is about 9MB/s.

The mini freezes are not unusual in my experience, I see it with Samba to a certain extent. The router will buffer writes in memory to a certain extent but there comes a point where it does not have any more memory and must wait for the physical I/O to complete (softirq). The router has a relatively small amount of RAM to play with.

You said the write speed was 1-2Mb/s, do you really mean "bits" or do you mean "bytes"?

Have you tried plugging the USB device into one of the other USB ports?

Also, have a look in the syslog. See if you can see what speed the USB interface was configured at when the device was detected.

 

[lawl]

Sorry, I meant bytes there. The flash drive that we are talking about is USB 2.0 and I am using it in the USB 3.0 port. On the 2.0 port of the router I have another flash drive with Entware on it. This second flash drive gets about 7MB/s on upload (freezes also present). Could the USB 3.0 port have problems?

If it helps, I have attached every occurrence of "USB" I have found in the system log. The storage drive is KINGSTON. https://pastebin.com/yaGcRmCK

 

[ColinTaylor]

Could the USB 3.0 port have problems?

It's definitely worth trying it in the USB2 port, if only as a test. There have been reports of devices not liking the USB3 port.

Also, it's worth changing the setting of Wireless > Professional > 2.4GHz > Reduce USB 3.0 interference to see if that makes a difference.

 

[lawl]

Disabling "Reducing USB 3.0 interference" seems to have done the trick. The upload starts now at 23MB/s and after a few freezes it gets down to 7MB/s. Also the CPU now reaches 80%, the RAM is still mostly used up. So thanks!
I saw that by uploading 2 files at the same time, the speed is very slow(~100KB/s) for both files and the CPU stays at 100%. Shouldn't the max speed be split between files?
Also, if I get an USB 3.0 flash drive, could the router handle higher speeds (in the range of 20-30MB/s) or it will just freeze until it gets to 7MB/s?

 

[ColinTaylor]

Low power routers like we have make for poor NAS's. I doubt whether there's much optimisation for concurrent I/O.

That said, according to the SNB review of similar routers you should be able to get about 23MB/s with a fast hard disk.

 

[lawl]

Ok, I will keep that in mind. Thank you for help!