Bug 142150

Summary:	large file transfer to nfs mounted folder intermittently peaks/stalls and on stall temporarily freezes konqueror
Product:	[Frameworks and Libraries] frameworks-kio	Reporter:	Dolf Andringa <dolf.andringa>
Component:	general	Assignee:	Alexander Neundorf <neundorf>
Status:	REPORTED ---
Severity:	normal	CC:	bugs, jjm, kdelibs-bugs-null
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Dolf Andringa 2007-02-24 18:43:55 UTC

Version: 3.5.5 (using KDE KDE 3.5.5)
Installed from: Ubuntu Packages
Compiler: gcc version 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)
OS: Linux

When I transfer files (big files, 1-multiple GB) in konqueror to an nfs mounted folder, the transfer speed peaks and stalls intermittently. The peak speed is between 25 and 30 MB/s (or 200-240MBit/sec) while the machines are on a 100MBit line with 100MBit LAN cards.
The average transfer speed is about right (around 80MBit) so it is not a problem with the cable. When the transfer speed stalls, konqueror freezes completely for some seconds, effectively freezing my whole KDE session. THen it resumes again, again at very high speeds. This goes on untill the file is transferred. In the end the file is transferred and at a good average speed as well, it is just very annoying that konqueror freezes constantly in between, making it very hard to do anything with my pc during the transfer.
I am suspecting that konqueror floods the tcp queue, then has to wait untill the ack packets are recieved (causing the stall) and resumes when the ack's are recieved, floods the queue again, etc. When I transferred the same files from the command-line, there was no freezing or other performance problems with the file transfer and it was completed in a good speed.

BTW I am running Ubuntu Edgy with Linux 2.6.17-11-generic #2 SMP Thu Feb 1 18:03:05 UTC 2007 x86_64 GNU/Linux
The nfs server is running Debian with Linux 2.6.16-2-686 #1 Wed Jun 21 17:35:13 UTC 2006 i686 GNU/Linux and nfs v3

Comment 1 Dolf Andringa 2007-02-24 19:15:28 UTC

Ok, this is not mainly a problem with konqueror file transfers but with kde file transfers (kio?). Other file managers under kde (Krusader for instance) show the same problem. Transferring files from the nfs mounted folder to the local filesystem is not a problem. Just from the local filesystem to an nfs mounted folder. By the way, I am running kde 3.5.5 (I did fill it in in the wizard but it is not shown in the report).

Comment 2 Matej Susta 2015-01-19 00:05:24 UTC

Hey there. Confirming this for Debian. It's already happening for several versions. This is definitely fault at KIO as both transfer speeds and system behaviour is normal when using command line tools or anything without KIO.
This happens with larger files that are able to fill out the rest of your available RAM. Because once the transfer of bigger file starts, Dolphin/KIO tries to read the file into memory *very* aggresively.

How to reproduce:
1. Mount any NFS
2. Copy / Move file from local system to remote NFS

What's happening:
- file transfer is slow
- Dolphin freezes

As hinted by #291835 I'll probably check how old is the NFS implementation in KIO.

Comment 3 Jonathan Marten 2021-02-05 14:26:12 UTC

Accessing NFS mounted folders is handled in the same way as local file access as far as KIO is concerned; that is, by the 'file' ioslave.  The NFS ioslave in kio-extras provides access to remote NFS servers (without the need for mounting) via URLs starting "nfs://host/".  Reassigning to frameworks-kio/general.