Linux Mint USB – Fix Slow Performance When Copying Files

linux-mintusb-drive

When I copy files to and from USB devices (camera, HDD, memory card) my system becomes very slow. For example if I want to close a window I move the mouse but it takes about 2 seconds or more before the mouse cursor moves. When I finally get the cursor over the x and click it nothing happens for 10+ seconds. I've tried this with all desktop effects disabled but the issue persists.

Software: Linux Mint 9 KDE
Hardware:

Asus SLI motherboard
NVidia 6600 GPU
2 GB Ram
2 GB Swap
AMD Athlox X2 @ 3800+

To me this hardware should not have any issues running this software and it doesn't until I copy files using USB. Where should I start looking to figure this one out? I'm kind of thinking the graphics driver may be part of the problem but I don't know for sure.

Best Answer

There seems to be a problem with huge pages in linuxes memory management. It rarely occurs, but sounds like you have observed it.

Cause

This is my grossly simplified account of what, according to the article, happens.

If unlucky, a process gets stuck the moment it issues a memory access. That's because when transparent huge pages is enabled, a memory access may trigger synchronous compaction (defragmentation of main memory,) synchronous meaning the memory access does not finish before the compaction does. This in itself is not a bad thing. But if write-back (of, e.g., buffered data to USB) happens to take place at the same time, compaction in turn is likely to stall, waiting for the write-back to finish.

So, any process could end up waiting for a slow device to finish writing buffered data.

Cure

Upgrading main memory, as the OP did, might help delay the problem. But for those who don't consider that an option, there are two obvious workarounds. Both involve recompiling the kernel:

disabling the transparent huge pages feature
applying Mel's patch as mentioned in the article

Related Solutions

USB Drive – Why PC Freezes When Copying Files to Pendrive

Are you using a 64-bit version of Linux with a lot of memory? In that case the problem could be that Linux can lock for minutes on big writes on slow devices like for example SD cards or USB sticks. It's a known bug that should be fixed in newer kernels.

See http://lwn.net/Articles/572911/

Workaround: as root issue:

echo $((16*1024*1024)) > /proc/sys/vm/dirty_background_bytes
echo $((48*1024*1024)) > /proc/sys/vm/dirty_bytes

I have added it to my /etc/rc.local file in my 64bit machines.

TANSTAAFL; this change can (and probably will) reduce your throughput to these devices --- it's a compromise between latency and speed. To get back to the previous behavior you can

echo 0 > /proc/sys/vm/dirty_background_bytes
echo 0 > /proc/sys/vm/dirty_bytes

...which are the default values, meaning that the writeback behavior will be controlled by the parameters dirty_ratio and dirty_background_ratio.

Note for the not-so-expert-with-linux people: the files in /proc are pseudofiles --- just communication channels between the kernel and user space. Never use an editor to change or look at them; get instead a shell prompt --- for example, with sudo -i (Ubuntu flavors) or su root and use echo and cat).

Update 2016/04/18 it seems that, after all, the problem is still here. You can look at it at LWN.net, in this article about writeback queues.

Linux – Diagnosing a mdm/Cinnamon freezing problem

Did you try this with different boot versions of the Petra installer? I used both Gnome version and LTE when I was having a similar issue booting over network/USB. I thought for sure it was a script going wrong somewhere and wasted countless hours on it. I later discovered it was a hardware controller malfunction by running Sandra diagnostics. If you run the MDM configuration script and everything comes off clean then your charging down the wrong path.