High System Load and UI Freezes with PSD under Specific Configurations #395
Description
Disclaimer: I want to preface this by stating that I do not believe this is a bug in PSD itself. It is likely a result of my specific system configuration, which, in combination, produces this adverse effect. However, it took me over a year to identify the correlation, so I decided to share my findings here in case it is helpful to others.
System Configuration:
- Laptop: Lenovo Thinkpad T14 Gen1 (AMD)
- RAM: 48 GB (16 GB + 32 GB)
- Storage: 1 TB NVMe Samsung 970 EVO
- Filesystem: EXT4 with the following mount options:
Note: The
/dev/nvme0n1p6 / ext4 rw,lazytime,commit=300 0 1commit=300option is used to keep dirty pages and caches in RAM longer. I consider this safe on a laptop with a battery.
PSD Configuration:
- I am using PSD with Firefox.
- The relevant setting in my configuration is:
(I am unsure if OverlayFS is the default now, but I recall when it was not available.)
USE_OVERLAYFS="yes"
Problem Description:
At random intervals, my system would experience severe UI freezes. The CPU would show 100% load across all cores, attributed to kernel-related processes (kworker). This was accompanied by intense disk I/O, so severe that the system became completely unresponsive (e.g., the mouse cursor would not move). Concurrently, the WiFi connection would drop, and kernel logs contained various driver error messages (which initially led me down the wrong path during my investigation).
Hypothesized Cause:
My current theory on the sequence of events is as follows:
- Firefox accumulates a significant amount of data in its profile during use.
- PSD, triggered by its timer, attempts to synchronize this data to the disk.
- This sync operation appears to run with high priority, consuming all system resources. The extensive I/O may also be interfering with the WiFi driver, causing disconnections.
- Once the data is fully written, the system returns to a responsive state.
I also have an unconfirmed impression that these freezes occur more frequently during activities like watching YouTube or listening music online. It's possible that these activities lead to a faster accumulation of profile data, though this is just an observation.
Current Status:
As a test, I disabled the PSD service in systemd. For over a week now, I have not experienced any of these system-freezing synchronization events. The system has been stable.
This further suggests that the interaction between my specific setup (long commit times, PSD, and Firefox's activity) was the root cause. I am reporting this not as a bug, but as a potentially useful data point for users with similar configurations.