Bug report: Mbed OS takes 30+ minutes to compile on an NTFS drive

Mbed OS Bugs
1

Hi,

When using Mbed Studio 1.4.4 on Ubuntu 20.04, Kernel 5.4.0, the mbed-os build process takes about 20 minutes and “Run program” is stuck on “Scan: APPNAME” in the “Output” tab for >10 minutes.

The project files are found on my Windows partition which is mounted as follows:

$ mount -l | grep pwin
/dev/sda2 on /media/pwin type fuseblk (rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096) [Windows]

Steps to reproduce:

  1. Have an NTFS drive mounted
  2. Try to compile mbed OS
  3. the process “mount.ntfs” slowly increases the CPU load from 0% to 100% (single core)
  4. Suffer
  5. At the end, the compiler kindly notifies you that it took more than 5 minutes to compile (no shit Sherlock!)

Moving the project to the Linux ext4 partition solves the issue. Thus I assume the IDE queries the same files too often or too fast, resulting in a full queue of operations to process by the ntfs-3g driver. Might there be optimization potential to reduce file lookups (recursive searches, for example?) or to at least warn the user when this configuration is used?

2

Hi,

Thank you for your post. We’ll make a note of it, but we probably won’t be able to investigate as there could be a number of reasons that could cause the slowness in your set up. (see https://www.reddit.com/r/linuxquestions/comments/73v5pi/why_is_ntfs_on_linux_so_slow/)

Many thanks

3

Thank you for the input. I changed fstab and after a reboot it does appear to build a bit faster. I however would rather not want to rebuild the entire thing because the mount.ntfs still shows a noticeable overhead (CPU usage) when loading the project.

I hope there’s potential for improvement in mbed Studio and that the new ntfs kernel driver will yield better performance in the future.